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Service IndicatorsDraft Standard

VITA 40-2002

Draft 0.4January 14, 200x

This standard is being prepared by the VITAStandards Organization (VSO) and is unapproved.

Do not specify or claim conformanceto this draft standard.

VSO is the Public Domain Administrator of this draft standardand guards the contents from change except by sanctioned

meetings of the task group under due process.

VITA Standards OrganizationP.O. Box 19658

Fountain Hills, AZ 85269Tel: 480-837-7486 Fax: contact VITA office

URL: http://www.vita.com

TABLE OF CONTENTS

Abstract ...................................................................................................................................iii

General Information (these sections will be deleted in the final standard)..............................ivPurpose ........................................................................................................................ivScope ............................................................................................................................ivTask Group Members ..................................................................................................ivVSO and Other Standards .............................................................................................vDraft Summary .............................................................................................................vDraft History ................................................................................................................vTask Group Ballot ........................................................................................................v

Chapter 1 ................................................................................................................................1Introduction to the Service Indicator Standard .................................................................1 1.1 Definitions .........................................................................................................................1 1.2 References .........................................................................................................................1 1.3 Standard Terminology .......................................................................................................1

Chapter 2 .................................................................................................................................3The Specification of the FRU-Level Service Indicator Standard .....................................3 2.1 Purpose and Background.....................................................................................................3 2.2 Indicator States or Behaviors ..............................................................................................3 2.3 Green .................................................................................................................................8 2.4 Yellow or Amber ................................................................................................................8 2.5 Blue ...................................................................................................................................9 2.6 White ................................................................................................................................11 2.7 Red ...................................................................................................................................12 2.8 Color Specification ...........................................................................................................13 2.9 Visibility Requirements .....................................................................................................14 2.10 Labeling ..........................................................................................................................17 2.11 Location and Mounting Order ........................................................................................18 2.12 Viewing Angle .................................................................................................................23 2.13 Size of Board Indicators ...................................................................................................24 2.14 Test Behaviors ..................................................................................................................24

Chapter 3 ................................................................................................................................25Applicability of Indicators as Enclosure Summary Displays .........................................25 3.1 Design Considerations for Summary Indicators .................................................................25

Appendix A ............................................................................................................................29Glossary....................................................................................................................................29

List of Tables

Table 2.2-1: The meaning of each permitted behavior ...............................................................4Table 2.2-2: The colors, behaviors, and meanings assigned to indicators . ...............................5Table 2.11-1: Indicator placement relative to standard board mounting holes ...........................18Table 3.1-1: Distinguishing characteristics of summary displays .............................................26

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List of Figures

Figure 2.2-1a: Graphical representations of timings for indicator behaviors .................................6Figure 2.2-1b: Graphical representations of timings for indicator behaviors .................................7Figure 2.10-1: Standard icons for each indicator type ..................................................................17Figure 2.11-1: Spacing of vertically mounted board or FRU indicators ......................................20Figure 2.11-2: Spacing of horizontally mounted board or FRU indicators ..................................21Figure 2.11-3: Spacing of vertically mounted board or FRU indicators using backlight ..............22Figure 2.11-4: Spacing of horizontally mounted board or FRU indicators using backlight .........23Figure 3.1-1: Spacing for summary indicators with icons above the indicators ...........................27Figure 3.1-2: Spacing for summary indicators with icons to the right of the indicators ..............27

List of Rules

Rule 2.2-1: The meanings of the permitted states or behaviors .....................................................4Rule 2.2-2: Permitted indicator behaviors for each color ..............................................................4Rule 2.2-3: Tolerances .................................................................................................................6Rule 2.3-1: The meaning of green ................................................................................................8Rule 2.3-2: The permitted states of green .....................................................................................8Rule 2.3-3: Application of green ..................................................................................................8Rule 2.4-1: The meaning of yellow or amber ...............................................................................8Rule 2.4-2: The permitted states of yellow or amber ....................................................................9Rule 2.4-3: The application of yellow or amber ...........................................................................9Rule 2.5-1: Meaning of blue .......................................................................................................10Rule 2.5-2: Permitted states of blue ............................................................................................10Rule 2.5-3: How blue is activated ...............................................................................................10Rule 2.5-4: Application of blue ...................................................................................................11Rule 2.6-1: Meaning of white .....................................................................................................11Rule 2.6-2: Permitted states of white ...........................................................................................11Rule 2.6-3: How white is activated ..............................................................................................12Rule 2.6-4: Application of white .................................................................................................12Rule 2.7-1: The meaning of red ..................................................................................................12Rule 2.7-2: The permitted states of red .......................................................................................13Rule 2.7-3: Application of the red indicator ................................................................................13Rule 2.8-1: Required colors .......................................................................................................13Rule 2.10-1: Standard icons .......................................................................................................18Rule 2.10-2: Placement of icons and labels ................................................................................18Rule 2.11-1: Mounting order of indicators .................................................................................18Rule 2.11-3: Fixed color positions .............................................................................................23.

List of Recommendations

Recommendation 2.1-1: Choice of colors and behaviors to implement on a particular product ..3Recommendation 2.4-1: Distinguishing "new" conditions from "old" conditions .......................9Recommendation 2.5-1: Blue should only be ON when specifically commanded .....................11Recommendation 2.5-2: Alert the user to the presence of other active blue lights ......................11Recommendation 2.6-1: Time limit on the FAST BLINK state of white ....................................12Recommendation 2.6-2: Alert the user to the presence of other active "locate" lights ................12Recommendation 2.8-1: How to operationally define white .......................................................13

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Recommendation 2.9-1: Indicators should be visible ..................................................................14Recommendation 2.9-2: Design and test for the expected operational conditions .......................15Recommendation 2.9-3: Visibility at DIRECT viewing angles and distances ............................15Recommendation 2.9-4: Visibility at SIDE viewing angles and distances ..................................15Recommendation 2.9-5: Visibility under different environmental lighting conditions ................16Recommendation 2.9-6: Illumination of back-lighted icons ........................................................17Recommendation 2.9-7: False illumination of indicators due to ambient light ............................17Recommendation 2.9-8: False illumination of indicators by adjacent indicators .........................17Recommendation 2.9-9: Equal luminance for all indicators on a single board or FRU ...............17Recommendation 2.11-1: Indicator placement ............................................................................18Recommendation 2.11-2: Avoid visual obstruction of indicators ...............................................19Recommendation 2.11-3: Spacing between indicators on boards ..............................................19Recommendation 2.12-1: Viewing angles of indicators ..............................................................23Recommendation 2.13-1: Board indicator size ...........................................................................24Recommendation 2.14-1: Power-on testing ................................................................................24Recommendation 2.14-2: Board insertion testing .....................................................................24Recommendation 2.14-3: Lamp inspection testing ......................................................................24Recommendation 3.1-1: Applicability of summary indicators.....................................................25Recommendation 3.1-2: Standard features of summary indicators ..............................................26Recommendation 3.1-3: Spacing between summary indicators ...................................................26

List of Observations

Observation 2.1-1: Non-uniformity of indicators ..........................................................................3Observation 2.2-1: Graphical representations of the ON/OFF timing for each behavior ...............6Observation 2.2-2: Choice of names for permitted behaviors ........................................................8Observation 2.4-1: How acknowlegement of new faults may be implemented ..............................9Observation 2.4-2: Definition of "system management facility" for acknowledging conditions ....9Observation 2.4-3: Use of the word "yellow" instead of "amber" .................................................9Observation 2.5-1: Why blue should be OFF until needed .........................................................11Observation 2.6-1: Why white uses FAST BLINK ...................................................................11Observation 2.6-2: Definition of "system management facility" to contol white..........................12Observation 2.6-3: Purpose of time limits on white ....................................................................12Observation 2.7-1: Use of red may be problematic .....................................................................12Observation 2.7-2: Why blinking red is not permitted ................................................................13Observation 2.9-2: Levels of illumination ...................................................................................16Observation 2.9-3: Adjacent indicators should be discernible from one another .......................16Observation 2.11-1: Why the mounting hole is used as a reference point ..................................18Observation 2.11-2: Indicator mounting on the board ................................................................19Observation 2.11-3: Use of red and white indicators on boards may be unusual .......................19Observation 2.11-4: Why 0.200 inch spacing between indicators is used ..................................19Observation 2.12-1: Use of non-clear lenses to increase viewing angle .....................................23Observation 2.14-1: The value of tests using the service indicators ...........................................24Observation 3.1-1: Red and blue summary indicators ................................................................25Observation 3.1-2: Summary indicators should be designed to aid users ...................................27Observation 3.1-3: Why summary indicators should be more prominent than board indicators .28

Abstract

This draft standard defines the colors, behaviors, placement, and labeling of service indicator lamps for boards, field replaceable units, and enclosures.

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General Information-------- parts of the following 7 sections may not be in the final standard ---------

Purpose

The purpose of this specification is to provide the information needed to design service indicators for boards, subsystems, and enclosures.

Sun Microsystems, Incorporated of Palo Alto, California, developed the specification of this service indicator standard but makes no proprietary claims to this specification or to any technique. SunMicrosystems disclaims responsibility or liability for its use, or for any infringement of patents or other rights of third parties resulting from its use.

Scope

This document describes a service indicator standard that seeks to be as compatible as possible with existing indicator standards and their extensions across different product markets. This standard addresses the meaning and application of specific colors to service indicators. This standard also defines and assigns meanings to specific approved behaviors or states for each color. It specifies where indicators must be placed and in what order, and it specifies luminance levels andviewing angles.

Task Group Members

When this standard was drafted, the Task Group for this standard had the following membership:

Name Status Company E-address

Ray Alderman P VITA [email protected] Chin P VISTA Controls [email protected] Cohen S Sun Microsystems, Inc. [email protected] Downing P Fermilab [email protected] Hartley Chair Sun Microsystems, Inc. [email protected] Heckman O Bustronic Corporation [email protected] Heslep P MITRE Corporation [email protected] Hom P APW Electronic [email protected] Koser S FCI Electronics [email protected] Macpherson S MITRE Corporation [email protected] Munroe S ERNI Components, Inc [email protected] Novak O Motorola Computer [email protected] Parsons P Tyco Electronics [email protected] Patterson P Tyco Electronics [email protected] Rush O Motorola Computer [email protected] Rynearson P VITA [email protected] Taylor P Bechtel Bettis Inc. [email protected] Thompson S NAVSEA Crane Division [email protected] Thompson S Pentair Electronic [email protected] Wong O Motorola [email protected]

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The "P" in the status column indicates participation in the ballot group.The "O" in the status column indicates Observers.The "S" in the status column indicates Sponsors

The following companies were on the sponsor balloting committee:

ERNI Components, IncFCI ElectronicsMITRE CorporationNAVSEA Crane DivisionPentair ElectronicSun Microsystems, Inc.

When the ANSI Standards Board approved this standard on xx/xx/200x, the balloting committee had the following membership:

TBD

VSO and Other Standards

For information on other standards being developed by VSO, VME Product Directories, VME Handbooks, or general information on the VME market, please contact the VITA office at the address or phone number given on the front cover.

Draft Summary

This current draft standard is a first draft and has not yet been reviewed. In the future, this draft standard will incorporate the comments received during the VSO ballot period and the ANSI ballot period when it is established.

Draft History

Version Date Comments

D0.1 May, 2002 First draft, derived from various documentsD0.2 September, 2002 Second draft circulated to subject expert reviewersD0.3 November, 2002 First draft to be released to the VITA40 group for ballotD0.4 January, 2003 Draft incorporating comments from ballots

Task Group Ballot

Task Group Ballot completed on December 4, 2002 with 18 votes FOR none AGAINST, and 4 not returned. Five voters approved with comments. Total Voters: 22; Returned Ballots: 18 (82%); Approve Ballots: 100%. The VITA 40 Draft passed according to VSO 75/75 criteria.

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Chapter 1

Introduction to the Service Indicator Standard

1.1 Definitions

See Appendix A for the glossary of the terminology specific to the features described in this standard.

1.2 References

The following publications were used to develop or are used in conjunction with this standard:

CIE 107-1994, Review of the Official Recommendations of the CIE for the Colours of Signal Lights

Engineering Data Compendium, Human Perception and Performance, Vol. I. Boff, JR and Lincoln, JE, Eds., 1988, AAMRL, Wright-Paterson AFB, OH

IEC NEC 73IEEE 1101-1-1998, Standard for Mechanical Core Specifications for Microcomputers

Using IEC 60603-2 Connectors IEEE 1101-10-1996, Standard for Additional Mechanical Specifications for

Microcomputers Using IEEE Std 1101.1-1991 Equipment Practice Ishihara Test for Color BlindnessMIL-STD-1472F, Dept. of Defense, Design Criteria Standard, Human EngineeringPICMG 2.0 R1.0 (full hot swap) CompactPCI Hot Swap SpecificationTelcordia Standard GR-2914-CORETelcordia Standard GR-474-CORETelcordia Standard GR-499-CORE

1.3 Standard Terminology

To avoid confusion and to make very clear what the requirements for compliance are, many of the paragraphs in this standard are labeled with keywords that indicate the type of information they contain. The keywords are listed below:

RuleRecommendationSuggestionPermissionObservation

Any text not labeled with one of these keywords describes the service indicator rationale or operation. It is written in either a descriptive or narrative style. These keywords are used as follows:

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Rule:

Rules form the basic framework of this draft standard. They are sometimes expressed in text form and sometimes in the form of figures, tables or drawings. All rules shall be followed to ensure compatibility between designs. All rules use the "shall" or "shall not" words to emphasize the importance of the rule. The "shall" and "shall not" words are reserved exclusively for stating rules in this draft standard and are not used for any other purpose.

Recommendation:

Whenever a recommendation appears, designers would be wise to take the advice given. Doing otherwise might result in some awkward problems or poor performance. It is possible to design an indicator system that complies with all the rules but has abysmal performance. In many cases a designer needs a certain level of experience in order to design indicator implementations that deliver top performance. Recommendations found in this draft standard are based on this kind of experience and are provided to speed the learning curve. The "should" and "should not" words are reserved exclusively for stating recommendations in this draft standard and are not used for any other purpose.

Suggestion:

A suggestion contains helpful but not vital advice. The reader is encouraged to consider the advice before discarding it. Some design decisions are difficult without prior experience. Suggestions are included to help a designer who has not yet gained this experience. Some suggestions pertain to designing indicators to be compatible with other boards or to avoid basic usability issues.

Permission:

In some cases, a rule does not specifically prohibit a certain design approach, but the reader might be left wondering whether that approach might violate the spirit of the rule or whether it might lead to some subtle problem. Permissions reassure the reader that a certain approach is acceptable and will cause no problems. The lower case word "may" is reserved exclusively for stating permissions in this draft standard and is not used for any other purpose.

Observation:

Observations do not offer any specific advice. They usually follow naturally from what has just been discussed. They spell out the implications of certain rules and bring attention to things that might otherwise be overlooked. They also give the rationale behind certain rules so that the reader understands why the rule must be followed.

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Chapter 2

Specification of the Service Indicator Standard

2.1 Purpose and Background

The purpose of this standard is to define consistent meanings for colors and behaviors of service indicators used on boards, subsystems, and enclosures.

The meanings assigned to each indicator color (i.e., red, white, blue, yellow, or green) are mutually exclusive. Similarly, the meanings assigned to each indicator behavior (e.g., SLOW BLINK, STEADY ON, OFF, etc.) are also mutually exclusive. Therefore, any combination of colors and behaviors visible at any one time merely represents a series of discrete messages, one per color (e.g., STEADY ON green means "the board is functioning"; SLOW BLINK yellow means "a new service action is required", etc.)

The meanings used in this standard for colors and behavioral states of indicators were derived from a variety of existing standards, guidelines, and supporting research studies. Every effort was made to find common ground among the various standards and guidelines. Wherever possible, key standards are cited in support of statements in this document. Most of these standards are based on extensive review and research, some with history going back 50 years.

The specific application of colors and behaviors to indicators should be based on the status information and feedback requirements of service personnel when performing service actions on the product (this application strategy is derived from from IEC 73).

Recommendation 2.1-1: Choice of colors and behaviors to implement on a particular product

As early as possible in the product design process, the product development team should develop an operational concept for the product. This concept should consider operational environments, technology, the expected skill level of service personnel, user tasks, diagnostic capability, etc.to determine what display information is required to minimize the probability of human error during servicing operations and to reduce the mean time to repair (MTTR). This analysis should yield a list of required indicator colors and their behaviors for the product.

Observation 2.1-1: Non-uniformity of indicators

Not every product will have every indicator color. Since the application of indicators to a product is based on an analysis specific to that product, not every product will have the same set of indicatorsand behaviors. However, those indicators that are present must comply with this standard. For example, if a board is not hot swappable, there is no need for it to have a "Service Action Allowed" i.e., "OK to remove" indicator.

2.2 Indicator States or Behaviors

MIL-STD-1472 indicates that users can distinguish among only a limited number of different blinking rates. Therefore this standard specifies only 4 very different and distinguishable blink rates. MIL-STD-1472 also specifies a normal blink rate of 4 +/- 1 Hz, which is very close to the IEC recommended maximum for normal flashing of 2.8 Hz. In addition, IEC 73 states that the

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ratio between two blink rates must be at least 1:2.5 in order for them to be distinguishable from one another (paragraph 4.2.3.2). We specify a fast blink rate of 4 Hz in this standard to go with the 1 Hz SLOW BLINK because we use FAST BLINK to call attention to the unit on which it appears.

The STANDBY BLINK behavior specified here was developed using hardware and software prototypes to simulate various ON/OFF timings over different intervals ranging from 2 to 4 seconds. Users preferred approximately 3 second intervals with minimal ON time to represent standby.

Each indicator color has a prescribed set of permitted states or behaviors. Indicators may have some or all of the behaviors permitted for that color, depending on whether they are useful in the operation of the particular product.

Rule 2.2-1: The meanings of the permitted states or behaviors

Each implementation of indicator behavior shall adhere to the meanings stated in Table 2.2-1.

activity is taking place commensurate with the flash rate (e.g., disk drive activity)

FEEDBACK FLASH

attention is required FAST BLINK

transitory activity or new activity represented by the color is taking place

SLOW BLINK

the system is functioning at a minimal level and ready to resume full function

STANDBY BLINK

the condition represented by the color is true

the condition represented by the color is not true

STEADY ON

OFF

MEANINGBEHAVIOR

Table 2.2-1: The meaning of each permitted behavior

Rule 2.2-2: Permitted indicator behaviors for each color

The permitted behaviors for each color of indicator shall be as defined by the following summary table: Table 2.2-2, “The colors, behaviors, and meanings assigned to indicators.”

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This indicator is not recommended for use except in specific environments like telco that require it.

This indicator is designed to help users locate a particular system or FRU

a normal activity is taking place for which direct, proportional feedback is desireable

This behavior is used to provide feedback that a transitory event is taking place. Slow blink is a temporary state. (e.g., POST) for which FEEDBACK FLASH is not feasible or appropriate.

a normal transitory activity is taking place for which direct proportional feedback is not needed or not feasible

This state is commonly used in laptops, energy efficient monitors, cell phones, etc.

the system is running at a minimum level and is ready to be quickly revived to full function

If blue is on, a service action can be performed on the applicable component with no adverse consequences.

The amber indicator stays on until the service action is completed and the system returns to normal function.

The purpose of this behavior is to make it possible to distinguish new faults from old faults

“normal”; system or component functioning with no service actions required

This behavior is used to provide feedback that normal activity is taking place. e.g., flickering light on a disk drive as it reads and writes data

“service action required”; the event has been acknowledged but the problem still needs attention

a new (unacknowledged) event requiring a service action has been detected

“out of service”

“here I am”

“service action allowed”

4Hz repeating sequence with equal ON/OFF time



steady state

steady state

steady state

steady state

steady statesteady state

steady state

steady statesteady state

Indicator is ON, but goes OFF during activity, e.g., disk drive access, message packets, shift between send and receive

Repeating sequence consisting of a brief (0.1 sec.) ON flash followed by a long OFF period (2.9 sec.)

FEEDBACK FLASH

SLOW BLINK

STEADY ON

STANDBY BLINKOFFGreen 525 nm

(Range: 505-535 nm)

(pure green is approx. 530 nm)

STEADY ON

SLOW BLINKOFFAmber 590 nm

(Range: 583-593 nm)

(traffic light yellow/amber is approx. 590 nm)

STEADY ONOFFBlue 470 nm

(Range: 445-480 nm)

(pure blue approx.is 450 nm)

FAST BLINKOFFWhite (defined as a

point of the CIE 1931 chomaticity diagram at approximately X=0.33, Y=0.35; see VITA40 text section 3.8 for an operational definition of white using data from observers)

STEADY ONOFFRed 630 nm

(Range: 615-650 nm)

(pure red is approx. 650 nm)

CommentMeaningDefinitionBehaviorColor (nm)

Table 2.2-2. The colors, behaviors, and meanings assigned to indicators.

Note: Colors have been selected to be separated from one another by approximately 3-7 color steps of 3 just-noticeable-differences (JNDs) each, according to published color research studies. Pure colors and

color ranges are as defined on the CIE 1931 chromaticity diagram.

(Ref.: Boff, KR and Lincoln, JE 1988 Engineering Data Compendium: Human Perception and Performance, Section 1.704, pp 332-333. AAMRL, Wright-Patterson AFB, OH

Rule 2.2-3: Tolerances

All the values in Table 2.2-2 shall be met within +/- 10%

Observation 2.2-1: Graphical representations of the ON/OFF timing for each indicator behavior.

The indicator behaviors may also be shown graphically as shown in Figures 2.2-1a and 2.2-1b below.

On

Off

STEADY ON

0 sec 1 sec 2 sec

...

On

Off

OFF

0 sec 1 sec 2 sec

...

Figure 2.2-1a. Graphical representations of timings for indicator behaviors.

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On

Off

STANDBY BLINK (100 ms ON followed by 2900 ms OFF)

0 sec 1 sec 3 sec

...

2 sec

On

Off

SLOW BLINK (1 Hz)

0 sec 1 sec 2 sec

...

On

Off

FAST BLINK (4 Hz)

0 sec 1 sec 2 sec

...

Figure 2.2-1b. Graphical representations of timings for indicator behaviors.

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Observation 2.2-2: Choice of names for permitted behaviors

The terms "SLOW BLINK" and "FAST BLINK" are used because they are descriptive of the relationship between the two symetrical (equal ON/OFF time) blink rates used in this standard (i.e., 1 Hz and 4 Hz).

2.3 Green

Green is commonly used to denote normal function. Many standards specify meanings for green. For example, MIL-STD-1472F section 5.2.2.1.13 states that "green shall be used to indicate that the monitored equipment is in tolerance or a condition is satisfactory and that it is all right to proceed (e.g., "in-tolerance", "ready", "function activated)". Similarly, Telcordia Standard GR-2914-CORE states that, "green shall indicate satisfactory operation, active condition, or completion of a process or procedure." International standard CEI IEC 73 section 4.2.1.1 assigns the meaning to green as a "normal" state of equipment or a "normal" condition of a process.

Rule 2.3-1: The meaning of green

Green shall mean "OK", "normal", "satisfactory operation", "active", or "in service". It indicates satisfactory operation, active condition, or completion of a process or procedure.

Rule 2.3-2: The permitted states of green

The permitted states or behaviors of green shall be OFF, STEADY ON, SLOW BLINK, STANDBY BLINK, and FEEDBACK FLASH. (Descriptions of these states are presented in section 3.2 above.)

Rule 2.3-3: Application of green

The green indicator shall apply only to the component or system on which it appears, i.e., the normal condition being indicated shall be isolated to the individual component or system.

2.4 Yellow or Amber

Yellow is commonly used to denote that the system or component requires attention or a service action, or that something is not functioning normally. MIL-STD-1472 states that, "yellow shall be used to advise an operator that a condition exists which is marginal" or "...to alert the operator to situations where caution, recheck, or unexpected delay is necessary." Telcordia GR-2914-CORE states that, "yellow or amber shall indicate minor failure, caution, warning, temporary malfunction, or state for which the craftsperson should use caution." International standard CEI IEC 73 section 4.2.1.1 assigns the meaning to yellow as an "abnormal" state of equipment or an "abnormal" condition of a process. The intent of yellow in this standard is to provide indication that aproblem exists somewhere on the component or system.

Rule 2.4-1: The meaning of yellow or amber

Yellow or amber shall mean "attention" or "service action required". Yellow or amber indicates a minor failure, caution, warning, or temporary malfunction, or state for which the service person should use caution.

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Rule 2.4-2: The permitted states of yellow or amber

The permitted states of yellow or amber shall be OFF, STEADY ON, and SLOW BLINK. (Definitions of these states are presented in section 3.2 above.)

Rule 2.4-3: The application of yellow or amber

The yellow or amber indicator shall apply only to the component or system on which it appears, i.e., the attention condition being indicated shall be isolated to the individual component or system.

The yellow or amber indicator functions as a fault indicator or annunciator. In many operational environments it is useful to be able to distinguish new fault conditions from conditions that are already known to the system operators. The ability to discern new faults from old can providevaluable information and feedback that can significantly increase the probability of error detection, minimize service errors, and reduce mean-time-to-repair. It is common practice in process-industry and aircraft-cockpit caution and warning (annunciator) panels to have fault indicators blink until acknowledged and then stay on until the fault is corrected. The SLOW BLINK state serves to call attention to the indicator while the STEADY ON state indicates the system or componentstatus. This basic provision is described in Telcordia GR-2914-CORE in rules R4-21 and R4-22, which apply to the user interface on the console associated with the network equipment.

Recommendation 2.4-1: Distinguishing "new" conditions from "old" conditions

Provision should be made for distinguishing new "attention" conditions from old (acknowledged) "attention" conditions by setting the state of yellow to SLOW BLINK when new conditions occur and changing the state of the yellow indicator to STEADY ON when the new condition has beenacknowledged through the service management facility.

Observation 2.4-1: How acknowlegement of new faults may be implemented

This standard does not specify how the system knows which conditions are acknowledged nor how to acknowledge them. Implementation is left to the board or system designer based on the requirements established for operational concept described in Recommendation 2.1-1 above. Examples of how acknowledgement might be made include automatic processes in the error alarm system, console commands, or an acknowledgement pushbutton on the board or enclosure.

Observation 2.4-2: Definition of "system management facility" for acknowledging conditions

A system management facility could consist of a console command, an automatic command from an on-board service processor, or even hardwired logic.

Observation 2.4-3: Use of the word "yellow" instead of "amber"

This document uses "yellow" to describe the "service action required" indicator. In reality, the color spectrum recommended is around 590 nm, which is best described as the color amber. Many potential users of the standard are not as familiar with amber as a color and often think of itas "yellow". "Yellow" is generally better understood than "amber".

2.5 Blue

The function of blue is to provide an active indication that it is safe to perform a service action (e.g., remove a component) while the system is running, i.e., there will be no loss or unacceptable

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degradation of service if the service action is performed. In this standard, blue is typically applied to hot swappable components to indicate when they are save to remove. The requirement for an active, rather than passive, indication for safe removal is a critical distinction and is one of the most important features of this standard. "Active" means that there is a distinct indicator that comes "on" to indicate "service action allowed" as opposed to having an indicator go "off" to indicate "service action allowed". An active indicator is unambiguous, whereas a passive indicator introduces uncertainty and ambiguity about whether or not it is OK to take a service action that could have major consequences (e.g., the indicator could be "off" due to a lamp failure). MIL-STD-1472F states that, "...the absence or loss of a signal or visual indication shall not be used to indicate a "ready" or "in tolerance" condition...". The provision of an active "OK to remove" indicator is a key requirement of Telcordia Standard GR-2914-CORE. Rule R5-1 states that, "There shall be one Light-Emitting Diode (LED) on each FRU (field replaceable unit), whose primary function shall be to indicate that the FRU can be pulled from the (network equipment or "NE") without interrupting any service (i.e., NE management or traffic) or causing damage to equipment or physical harm to the technician."

The choice of the color blue for this indicator is based on the need to provide a color that is technically feasible, distinguishable in appearance from the other colors used in this standard, and has no meaning stereotype that contradicts the message intended. MIL-STD-1472F allows use of blue as an "advisory light". CEI IEC 73 allows use of blue for "mandatory significance", i.e., to indicate something that is associated with a required action. In contrast, Telcordia GR-2914-GR uses red for the "OK to remove" indicator, but red also has the meaning in the telecommunications environment of "out of service", as described in section 3.2 above. A research study at a computer systems company showed that system administrators interpreted red as meaning "stop" and expressed a strong preference for a blue rather than red to indicate that it was OK to proceed with a service action. The GR-2914-CORE project manager, in a personal communication, stated that the key requirement of GR-2914-CORE was the provision of an active indicator and that the color used was of less importance. Finally, blue is presently used in the electronic board industry to indicate that a board is unclaimed by the system and is therefore "OK to remove" or that a "service action is allowed" (e.g., see “Live Insertion for VME64x”, VITA 1.4-199x, (latest draft) and “CompactPCI Specification” PICMG 2.1 R1.0 (full hot swap) ). Rule 2.5-1: Meaning of blue

Blue shall mean "Service Action Allowed". It indicates that a service action (e.g., hot swapping) can be performed without interrupting any service or causing damage to equipment or physical harm to the technician.

Rule 2.5-2: Permitted states of blue

The permitted states of blue shall be OFF and STEADY ON. (Definitions of the states are presented in section 2.2 above.)

Rule 2.5-3: How blue is activated

Blue shall be turned to STEADY ON only through a specific command issued by the service management facility. The service management facility may be automatic or manual.

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Recommendation 2.5-1: Blue should only be ON when specifically commanded to be ON through the service management facility

Just because a board can be removed from service at any time without adverse consequences does not mean that blue should always be ON. Instead, blue should be OFF until there is a specific request issued by the service management facility to verify that the board can be removed.

Recommendation 2.5-2: Alert the user to the presence of other active blue lights

When blue is turned ON from a console command, the console operator should be notified if any other blue lights are already turned ON in the data center, where they are located, and how much time remains until they will turn OFF.

Observation 2.5-1: Why blue should be OFF until needed

By having blue be ON only when specifically commanded to be ON, the number of indicators illuminated on the system at any given time is minimized. This makes it easier to identify specific boards and enhances the visibility and utility of the blue when it is needed. Implementation of blue should always be based on an analysis of the service strategy for the product.

Rule 2.5-4: Application of blue

The blue indicator shall apply only to the component or system on which it appears, i.e., the service action allowed shall be isolated to the individual component or system.

2.6 White

The function of white is to provide an aid to locating a particular system or subassembly. This function is especially valuable for enclosures installed in environments where there may be numerous identical unit in operation. In order to make the locator indicator be more noticeable, it uses a distinctive FAST BLINK that is very different from the SLOW BLINK used by other indicators.

Rule 2.6-1: Meaning of White

White shall mean "here I am" or "this is the item being sought". White indicates a neutral condition that implies nothing about the success or failure of system operations.

Rule 2.6-2: Permitted States of White

The permitted states of white shall be OFF and FAST BLINK. (Definitions of the states are presented in section 2.2 above.)

Observation 2.6-1: Why white uses FAST BLINK

White is a normal lighting color in most operational environments. In order to make the white locate function stand out in its operational environment, the light blinks at an exceptionally noticeable fast rate that is unusual in the operating environment.

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Rule 2.6-3: How white is activated

White shall only be turned on to FAST BLINK as a result of a specific command from the service management facility.

Rule 2.6-4: Application of white

The white indicator shall apply only to the component or system on which it appears, i.e., the locator function being indicated shall apply to the individual component or system.

Observation 2.6-2: Definition of "system management facility" to contol white

A system management facility could consist of a console command, an automatic command from an on-board service processor, or even hardwired logic.

Recommendation 2.6-1: Time limit on the FAST BLINK state of white

The duration of the FAST BLINK state on white should be limited to 30 minutes.

Recommendation 2.6-2: Alert the user to the presence of other active "locate" lights

When the FAST BLINK state of white is turned on from a console command, the console operator should be notified if any other white lights are already turned on in the data center, where they are located, and how much time remains until their indicator will turn OFF.

Observation 2.6-3: Purpose of time limits on white

The purpose of Recommendation 2.6-1 is to ensure that a time-out function is implemented in order to prevent the locate function from remaining on indefinitely and to minimize the probability that multiple locate indicators are on at the same time. The 30-minute limit is based on interviews with computer system administrators and their estimates of a reasonable amount of time to locate a system in a typical operational environment.

2.7 Red

Where red indicators are mandated (e.g., some telco installations):

Rule 2.7-1: The meaning of red

Red shall mean "out of service", "major fault", or "critical fault". Red indicates a critical or major failure, error, or danger.

Observation 2.7-1: Use of red may be problematic

Use of red may be problematic in environments where red has special meaning. For example, a red warning indicator in an industrial environment may be used to alert personnel to life threatening conditions, physical danger, fire, or emergency exits. MIL-STD-1472F assigns the meaning,"...system...inoperative...no go, error, failure, malfunction". When red is used in the context of this standard, it must have a distinct and unambiguous meaning in relation to the other colors.

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Rule 2.7-2: The permitted states of red

The permitted states of red shall be OFF and STEADY ON.

Observation 2.7-2: Why blinking red is not permitted

Blinking red is not permitted because this state has strong connotations in most environments that there is impending danger or the possibility of personal injury.

Rule 2.7-3: Application of the red indicator

The red indicator shall apply only to the component or system on which it appears or with which it is clearly associated, i.e., the individual component or system on which the red indicator appears shall be out of service.

2.8 Color Specification

Colors are stated in nanometers (nm) or, in the case of white, in an operational test of light sources having values close to color space x and y coordinates on the CIE 1931 chromaticity diagram. The definition of white is problematic because various lamp manufacturers define it differently and generate it by blending values for R, G, and B. Therefore this standard describes an operational test to verify that users see the color as white (see Recommendation 3.8-1 below).

The colors specified here have been selected to be separated from one another by approximately 3-7 color steps of 3 just-noticeable-differences (JNDs) each, according to published color research studies. Pure colors and color ranges are as defined on the CIE 1931 chromaticity diagram. (See ref.: Boff, KR and Lincoln, JE 1988 Engineering Data Compendium: Human Perception and Performance, Section 1.704, pp 332-333. AAMRL, Wright-Paterson AFB, OH.) These particular colors were also selected because they are technically feasible and commercially available.

Rule 2.8-1: Required colors

The colors to be used in this standard shall be:

Green = 525 nm (allowable range 505-535 nm) Amber = 590 nm (allowable range 583-593 nm) Blue = 470 nm (allowable range 425-480 nm) Red = 630 nm (allowable range 615-660 nm) White = see definition method in Recommendation 2.8-1 below

Recommendation 2.8-1: How to operationally define white

White is defined roughly as a point on the CIE 1931 chromaticity diagram at X=0.35, Y= 0.33. Unfortunately, some implementations of white may appear to be slightly some other color, and methods for defining white vary from manufacturer to manufacturer. Perception of a whiteindicator as being another indicator color could increase the probability of a service error. Therefore white indicator implementations should be tested to verify that users see them as white. This verification test is not required for the other colors.

The color identification validation for white can be accomplished by conducting a test (method derived from Telcordia GR-2914-CORE) as follows:

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Participant Characteristics: The participants should be individuals who are unfamiliar with the product or the exact purpose of the test. Each should have 20-20 natural or corrected vision and normal color vision according to the Ishihara Test for Color Blindness (see http://www.toledo-bend.com/colorblind/Ishihara.html).

Test Article: The indicator implementation that is tested should be the same as the implementation on the final product. In other words, if the light source is to be viewed after passing through a light pipe, then the test should be conducted on the light source passing through the same light pipe. It is possible that transparent or translucent media may cause the color to shift and for the white light to be seen as some other color. The luminance of the test article should be established using the method in Recommendation 2.9-4 below.

Illumination: Ambient illumination for the test should be typical of computer room or central office equipment areas (50-100 fc). The luminances of surfaces immediately adjacent to the indicator being tested should be at least one-third that of the ambient illumination level, and they should not exceed the luminance of the ambient illumination level.

Procedure: The participant should stand in a predetermined starting position 1m distance in front of the product with visibility to the target perpendicular (horizontally and vertically) to the surface on which it is mounted. The target area or components should not be visible until the start of the task has been designated. Once the task has started, the target area or component should be visible. When all is ready, the experimenter should command the indicator to turn on and the participant should detect and state the indicator color within 10 seconds (i.e., answer the question: "What is the color of the light?"). Each participant should be tested individually. No other participantsshould be present.

Color Acceptance Criteria: The correct color of the indicator ("white") should be identified correctly by 9 out of 10 participant observers at a distance of 1m from a position directly in front of the product. The 9 correct participant observers may not have any false responses (i.e., saying a different color and then changing their decision). With each round of testing, only 10 participants should be tested at a time. In other words, 9 out of 10 in the round of testing must ascertain thecolor correctly for the color identification criteria to be met.

2.9 Visibility Requirements

In order to be effective, indicators must be bright enough to be seen under the expected viewing conditions for the product. Failure to provide indicators with sufficient brightness makes it difficult or impossible to quickly and accurately determine system status thereby making the situation ambiguous and increasing the probability of human error in operation, servicing, or maintenance.

An analysis of the product and its expected operational environments should be conducted to ascertain environmental conditions and required viewing angles for all indicators. For example, if the product could be mounted in the highest or lowest position in a rack, the indicators must be viewable from below or above. If it could reasonably be expected to be used in bright light or even daylight, then all indicators should be sufficiently bright for daylight use. Conversely, if the product could be used in low illumination, then it should have the ability to "turn down" the brightness.

Recommendation 2.9-1: Indicators should be visible

All indicators should be visible at their expected operational viewing angles and distances and under their expected environmental lighting conditions.

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Recommendation 2.9-2: Design and test for the expected operational conditions

The target market or use for each product should be assessed to determine the likely operational conditions under which the product will be used. These conditions may include such things as mounting height (minimum and maximum), environmental lighting conditions, and user characteristics and qualifications (e.g., is color blindness tested?). These conditions should be documented, and any qualification testing should be modified as appropriate to ensure that the product will be operable in all expected conditions.

Recommendation 2.9-3: Visibility at DIRECT viewing angles and distances

Indicators should be visible when seen from directly in front of the product, in other words, perpendicular to the indicator mounting surface and passing through the center of the indicator (i.e, "normal" or 90 degrees horizontally and vertically from the mounting surface).

This visibility requirement can be verified empirically by conducting a test (derived from Telcordia GR-2914-CORE) as follows:



Procedure: The participant should stand in a predetermined starting position 5m distance and in front of the product with visibility to the target perpendicular (horizontally and vertically) to the surface on which it is mounted. The target area or components should not bevisible until the start of the task has been designated. Once the task has started, the target area or component should be visible. When all is ready, the experimenter should command the indicator to turn on and the participant should detect and note the indicator status within the prescribed time. Each participant should be tested individually. No other participants should be present.

Visibility Acceptance Criteria: The correct status of each indicator (color and ON/OFF condition) should be detectable within 10 seconds by 9 out of 10 participant observers at a distance of 10m from a position directly in front of the product. The 9 correct participant observers may not have any false responses (i.e., saying a status or color and then changing their decision). With each round of testing, only 10 participants should be tested at a time. In other words, 9 out of 10 inthe round of testing must ascertain the status correctly for the visibility criteria to be met.

Recommendation 2.9-4: Visibility at SIDE viewing angles and distances

Indicators should be visible in all directions at a side angle 60 degrees off of a line that is perpendicular to the indicator mounting surface and passing through the center of the indicator (i.e, forming a 120 degree field of view cone around the indicator).

This visibility requirement should be verified empirically by conducting a test as follows:

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Procedure: The participant should stand in a predetermined starting position (10m distance and at a 60 degree angle to one side). The target area or components should not be visible until the start of the task has been designated. Once the task has started, the target area or component should be visible. When all is ready, the experimenter should command the indicator to turn on and the participant should detect and note the indicator status within the prescribed time. Each participant should be tested individually. No other participants should be present. In order to test visibility in the "up" and "down" directions as well as side-to-side, the product should be rotated 90 degrees and the test repeated as if it were side-to-side.

Visibility Acceptance Criteria: The correct status of each indicator (color and ON/OFF condition) should be detectable within 10 seconds by 9 out of 10 participant observers at a distance of 5m at a side angle of 60 degrees. Five of the 10 participants should view the product fromone side and five should view it from the other side. The 9 correct participant observers may not have any false responses (i.e., saying a status or color and then changing their decision). With each round of testing, only 10 participants should be tested at a time. In other words, 9 out of 10 in the round of testing must ascertain the status correctly for the visibility criteria to be met.

Recommendation 2.9-5: Visibility under different environmental lighting conditions

Indicators should be visible under both bright illumination (incandescent or fluorescent - 50-100 fc) and low illumination conditions. If the product may be used in low illumination conditions(e.g., in a "lights out" environment), then the tests described in Recommendations 2.9-4 and 2.9-5 should be repeated with low ambient illumination (5-10 fc). A good rule of thumb in low light conditions is that there should be a minimum contrast ratio of 20:1 between the indicator and adjacent surfaces.

Observation 2.9-2: Levels of illumination

It may be desirable to provide at least two levels of illumination (high and low) so that the indicator can be used effectively under both bright and low-illumination conditions. In order to be seen in bright light, indicators should be very bright, but under low light conditions, too much brightness may be problematic as the indicators may appear larger and brighter and obscure other, adjacent indicators.

Observation 2.9-3: Adjacent indicators should be discernible from one another

It should be possible to discern the status of different adjacent indicators when they are on. Some colors may appear brighter than others (particularly green because of the eye's differential sensitivity) and as a result, they may "bloom" and dominate or obscure other adjacent indicators. If this is a possible problem, the visibility tests recommended above should be repeated with multipleindicators on at the same time. Adjustments may be made in brightness to ensure that adjacent indicators are discernible from one another.

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Recommendation 2.9-6: Illumination of back-lighted icons

Back-lighted icons should be evenly illuminated. The contrast ratio between the brightest and the darkest part of the icon should not exceed 1.5:1.

Recommendation 2.9-7: False illumination of indicators due to ambient light

Some indicators may reflect ambient light and appear to be illuminated when they are not energized. Indicators should not appear to be ON when they are OFF.

Recommendation 2.9-8: False illumination of indicators by adjacent indicators

The light from an active indicator should not illuminate another, adjacent, inactive indicator so that it appears ON when it is actually OFF.

Recommendation 2.9-9: Equal luminance for all indicators on a single board or FRU

The human eye is more sensitive to some colors than others. The luminance of all indicators on a single board should appear roughly equal (e.g., the green indicator should not appear to be brighter than the yellow indicator when both are on at the same time, etc.)

2.10 Labeling

Standard icons for each indicator type are shown in figure 2.10-1 "Standard Icons for Each Indicator Type". Details about spacing, location, and industrial design details are shown in Figure 2.10-2, "Standard Spacing and Placement for Each Indicator Type".

Figure 2.10-1. Standard icons for each indicator type, showing different foregrounds/backgrounds

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Rule 2.10-1: Standard icons

The standard set of icons shown in Figure 2.10-1 shall be used for all service indicators.

Rule 2.10-2: Placement of icons and labels

Labels and icons for non-backlighted indicators shall always be placed above or to the right of the indicator. Backlighted indicator icons shall be placed where the indicator lamp would normally be placed.

2.11 Location and Mounting Order

The service indicator group location on the system or component is generally in the upper left corner or uppermost and leftmost in the space available.

Rule 2.11-1 Mounting order of indicators

The indicators shall be mounted in the following order:red (top or left) white (space) blue yellow green (bottom or right)

Recommendation 2.11-1: Indicator placement

The indicators should be installed as closely as possible to the middle of the short side of the front panel of a board, using the distances from the mounting hole at the top (or left) edge of the board as shown in Table 2.11-1 and spacing as shown in Figures 2.11-1 through 2.11-4 below.

35mm +/- 1mm from the center of the mounting hole





GreenYellowBlueWhiteRed

PlacementColor

Table 2.11-1: Indicator Placement relative to a standard board mounting hole

Observation 2.11-1: Why the mounting hole is used as a reference point

The location of the topmost indicator is dictated by VITA standard board mounting hole and ejector handle locations (see VME64 (ANSI/VITA 1-1994)). Using the mounting hole as a standard reference point will cause all the indicators to line up across all boards mounted in the same chassis.

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This consistency of placement aids the user in detecting changes in status more quickly because a break in a pattern is more easily detected than a change in status of a single LED in a random location.

Observation 2.11-2: Indicator mounting on the board

Indicators may be mounted on the component or solder sides of the board as long as they are still visible. In general, every effort should be made to mount the indicators as closely as possible to the middle of the short dimension of the board so their visibility can be maximized.

Observation 2.11-3: Use of red and white indicators on boards may be unusual

It is expected that most boards or FRUs will not have a red indicator. Red should only be used in environments where standards mandate its use (e.g., telco). When it is used, it can only have one meaning: "out of service". Similarly, it is expected that the white “locate” function will be used on the enclosure but not on individual boards. This means that arrays of indicators on boards or FRUs will typically consist of blue, yellow, and green only.

Recommendation 2.11-2: Avoid visual obstruction of indicators

Indicators may be obscured if other components are placed where they can interfere with indicator visibility. Visual obstruction of the indicators should be minimized by anticipating potential problems and taking appropriate action to mitigate them (e.g., mounting cable connectors below service indicators, providing for cable dressing, anticipating multiple systems or components in a rack or enclosure).

Recommendation 2.11-3 Spacing between indicators on boards

Spacing between indicators on boards or FRUs should be based on multiples of 0.200 inch or 5.08 mm.

Observation 2.11-4: Why 0.200 inch spacing between indicators is used

Indicator spacing is based on the LED industry standard multiples of 0.200 inch or 5.08 mm. This helps reduce the cost of implementing the standard because custom parts are not required and multiple vendors supply compatible parts. The 5.08 spacing is preferred over tighter spacing (<5.0 mm) because wider spacing allows more room for effective icons and labels.

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(NOTE: Not all indicators may be needed for a given enclosure. If an indicator is not used, that space is left blank)

Figure 2.11-1: Spacing of vertically mounted board or FRU indicators

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Figure 2.11-2: Spacing of horizontally mounted board or FRU indicators

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Figure 2.11-3: Spacing of vertically mounted board or FRU indicators using dead-frontor backlighted icons

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Figure 2.11-4: Spacing of horizontally mounted board or FRU indicators using dead-front or backlighted icons

Rule 2.11-3: Fixed color positions

Boards or FRUs that do not implement all the 5 colors, shall mount the remaining indicators according to Rule 2.11-1 (i.e., do not condense the light array) in order to maintain alignment of all like colors across similarly mounted boards or FRUs on the enclosure.

2.12 Viewing Angle

Wide viewing angle is required so that indicator status can be accurately and quickly discerned no matter where the indicator array is located in a rack or enclosure.

Recommendation 2.12-1: Viewing angle of indicators

Indicators should be viewable at a 60 degree angle from perpendicular to the mounting surface in all directions (i.e., a cone). See section 2.9 above for details about how visibility should be measured.

Observation 2.12-1: Use of non-clear lenses to increase viewing angle

Frosted LED lenses are recommended to increase viewing angle on direct view LEDs. When clear lenses are used on LEDs that are viewed directly, the emitter element is a bright point of light that is highly directional. Frosted lenses disburse the light over the surface of the LED and improve its viewability from all angles.

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2.13 Size of Board Indicators

Recommendation 2.13-1: Board indicator size

Board indicators, or indicators of any field replaceable unit (FRU) adhereing to this standard, should be 3 mm or less in their largest dimension so they can be distinguished from enclosure summary indicators, which should be 5mm or larger (see section 3.0 below). Board or FRU indicators should be no smaller than 1.5 mm.

2.14 Test Behaviors

The service indicators may be useful for providing feedback during power-on, board insertion, or lamp testing.

Recommendation 2.14-1: Power-on testing

If the service indicators are used for power-on testing, every indicator in the set of indicators on each board or FRU should SLOW BLINK in unison for no less than 1 second and no more than 5 seconds. If multiple boards in a system enclosure are tested at power-on, it is recommended that the test be conducted in ordered sequence throughout the enclosure from left to right, top to bottom, then front to back.

Recommendation 2.14-2: Board insertion testing

Boards and FRUs should self-test on insertion to provide immediate feedback that the board or FRU has been inserted correctly. If the insertion test is implemented, every indicator in the set of indicators on the board or FRU should SLOW BLINK in unison for no less than 1 second and no more than 5 seconds.

Recommendation 2.14-3: Lamp inspection testing

Boards and FRUs should incorporate a lamp inspection test capability so that it is possible to confirm that no lamps are burned out or otherwise non-functional. Lamp tests should be implemented through a momentary push button on the enclosure that, while depressed, illuminates all the lamps on that side of the enclosure, in unison. Lamp tests may also be performed through a software command, but these tests should have a time-out function so that the indicators return to their current valid state in less than 30 seconds.

Observation 2.14-1: The value of tests using the service indicators

Tests using the service indicators can be very useful because they can reduce the mean time to make repairs and minimize the probability of service errors by providing service personnel with timely and unambiguous confirmation that the indicators are functional. Tests may also be very useful in quality control testing of indicators during manufacturing.

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Chapter 3

Applicability of Indicators as Enclosure Summary Displays

The indicators described in this document may be applied to larger units such as enclosures and racks. When applied to larger units, they function as summary displays representing the status of components inside the unit. Indicator meaning and application must remain the same, whether they apply to a board, FRU, or to a larger unit containing many FRUs. For example, an enclosure containing multiple boards, each with its own set of service indicators, might have a summary set of service indicators to help guide a service person to the unit in order to more quickly locate a faulty board. The enclosure might have, as a minimum, a green indicator and a yellow indicator. If green is STEADY ON, then at least one subunit within the enclosure is performing some normal function, if yellow is STEADY ON, then some subunit in the enclosure requires a service action that has been acknowledged, if yellow is blinking (SLOW BLINK) then there is a new, unacknowledged, condition requiring a service action. If white is FAST BLINK then the enclosure is the one being sought. It is possible that the service person would locate the enclosure using the white indicator and then look for a particular board in that enclosure with a blue indicator STEADY ON that is ready for a service action. It may not be appropriate to have a blue indicator at the enclosure level because blue means service action allowed on the enclosure (i.e., the entire enclosure may be taken out of service). This may not be common, but it is possible, depending on the service model for the product. It is critical that the meaning of the blue indicator (or any other indicator that may be used at the system summary level) be consistent with the rest of this standard. In other words, ifblue is used, a service action affecting the whole unit may be performed with no adverse consequences. By applying the indicator standard in this way, it is possible to aid service personnel in locating boards or FRUs that need service attention and in directing service actions.

3.1 Design Considerations for Summary Indicators

Recommendation 3.1-1: Applicability of summary indicators

The summary indicators apply to the unit as a whole. Each summary indicator should be consistent with this standard in meaning, use of color, labeling, and behavior. Green means normal function is taking place in the enclosure. Yellow means a service action is required. White is a locator beacon for the whole enclosure. Blue and red indicators should only be used as part of the summary indicator group when the whole enclosures is hot swappable or when the whole enclosure is out of service.

Observation 3.1-1: Red and blue as summary indicators

Red and blue indicators may be provided inside the standard summary indicator area only if their use is appropriate, i.e., red indicates that the ENTIRE ENCLOSURE is "out of service"; blue indicates the ENTIRE ENCLOSURE may be subject to a service action, such as hot swap, or complete removal of power for cold servicing, without any adverse consequences.

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Recommendation 3.1-2: Standard features of summary indicators

Summary indicators should be made clearly distinguishable from FRU status indicators by employing multiple coding strategies to differentiate them. These strategies are summarized in Table 3.1-1 and include: size (i.e., use 5 mm indicators instead of 3 mm indicators), brightness, location, grouping, spacing, background color, and labeling. The summary indicators should be distinctively set off so that a service person can locate them immediately, recognize them as summary indicators, and act effectively on their meaning. Summary indicators should always be located in the upper left corner of the enclosure, and they should appear in a distinctive black rectangular background area with a white border. The industrial design of the summary indicatorsfor any product should show clearly (unambiguously) that summary displays apply to the whole unit and not to any individual sub-component.

2 pt. border line thickness

white on black area border color

white label and icon color

65 mm X 13.5 mm or 65 mm X 8 mm background panel size

black background panel color

80 degrees preferred; not obstructed viewing angle

horizontal preferred, vertical allowed orientation

upper left corner of enclosure location

noticeably greater than FRU brightness brightness

2 X units (12.70 mm between LED positions) spacing between indicators

6.35 mm (0.25 inch) (vs 5.08 mm for FRUs) units of spacing

5mm (vs 3 mm for FRU LEDs) LED size

CHARACTERISTICS FEATURE

Table 3.1-1. Distinguishing Characteristics of Summary Displays

Recommendation 3.1-3: Spacing between summary indicators

The spacing between indicators, whether mounted horizontally or vertically should be as shown in Figures 3.1-1 and 3.1-2:

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Figure 3.1-1. Spacing for summary indicators with icons above the indicators


Figure 3.1-2. Spacing for summary indicators with icons to the right of the indicators

Observation 3.1-2: Summary indicators should be designed to aid users by providing a few essential facts about the sub units in the enclosure

Summary indicators should allow easy confirmation of unit identification (using the FAST BLINK white indicator) and summarize the status of the components within the enclosure (using the green and yellow indicators). For example, if at least one FRU within the enclosure requires a service action, then the yellow summary indicator would be illuminated; or if at least one component within

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the enclosure is functioning normally, then the green summary indicator would be illuminated. The basic information should lead the user step by step to the correct service action. For example, a service person could see a yellow light on a rack summary display and conclude there is a component somewhere in the rack that needs service attention. She or he could then open the rack door and see a yellow indicator on a board needing attention.

Observation 3.1-3: Why summary indicators should be more prominent than board indicators

Summary indicators should be noticeably larger (5 mm vs 3 mm) and brighter than indicators on FRUs so they are easily distinguishable from board or FRU indicators.

SI, VITA 40-200x/D0.4 page 28 1/14/03

Appendix A: Glossary

acknowledge: recognize the status of a board, component, process, or system by taking some action to send a signal to the host of that board, component, process, or system

amber (also see yellow): the color used in this standard to indicate that a service action is required; nominally 590 nm in this standard with an acceptable range of 583-593 nm; the color specified in this standard is actually amber, but to facilitate understanding of the standard, “yellow” and “amber” are used interchangeably (as in “yellow” for a traffic light)

annunciator: an electrically controlled signal board or indicator used to display system condition or to alert the operator to changes in system state

behavior: the way in which something functions or operates; in this standard used interchangeably with “state” (see also state)

blinking: an intentional periodic change in the luminous intensity of a display element such as an LED.

blue: the color used in this standard to indicate that a service action is permitted; nominally 470 nm in this standard with an acceptable range of 425-480 nm

board: a printed circuit board including its components and mounting hardware

chromaticity, chromaticity coordinates: dimensions of a color stimulus expressed in terms of hue and saturation, or redness-greenness and yellowness-blueness, excluding the luminous intensity; generally expressed as a point in a plane of constant luminance. (See CIE xy Chromaticity Diagram.)

CIE xy chromaticity diagram: a two-dimensional graph of the chromaticity coordinates, x as the abscissa and y as the ordinate, which shows the spectrum locus (chromaticity coordinates of monachromatic light, 380-770nm); it has many useful properties for comparing colors of both luminous and nonluminous materials.

color: the phenomenon of color results from the interaction between a light source, an object and an observer. Standard mathematical models can be used to quantify light source, objects and observers as a function of wavelength. Sources are quantified as illuminants, objects are quantified by spectral data, and observers are quantified by the observer functions. These three elements can then be combined to calculate values that correspond to how the human visual system responds to a given color.

component side (also see solder-side): the side of a printed circuit board on which the majority of the electronic components are mounted.

dead front: a backlighted display which appears blank until the light is turned on; usually appears as a lighted icon or lable when illuminated

enclosure: the mechanical structure that houses the components of the system, e.g., a sheetmetal chassis

SI, VITA 40-200x/D0.4 page 29 1/14/03

fault: 1. an accidental condition that causes a functional unit to fail to perform its required function. 2. a defect that causes a reproducible or catastrophic malfunction. Note: A malfunction is considered reproducible if it occurs consistently under the same circumstances. 3. In power systems, an unintentional short-circuit, or partial short-circuit, between energized conductors or between an energized conductor and ground.

feedback: 1. the return of a portion of the output, or processed portion of the output, of a (usually active) device to the input. (188) Note 1: The feedback signal will have a certain magnitude and phase relationship relative to the output signal or the input signal. This relationship can be used to influence the behavior, such as the gain and stability, of the overall circuit. Note 2: If the feedback is regenerative (additive), it is called "positive feedback," which increases gain and distortion, and decreases linearity and stability. Note 3: If the feedback is degenerative (subtractive), it is called "negative feedback," which reduces the gain and distortion, and increases linearity and stability. Note 4: Feedback may occur inadvertently, and be detrimental. 2. Information returned as a response to an originating source.

field-replaceable unit (FRU): a circuit board or other system part that can be quickly and easily removed and replaced by the user or by a technician without having to send the entire product or system to a repair facility

green: the color used in this standard to indicate that the component or system is functioning normally; nominally 525 nm in this standard with an acceptable range of 505-535 nm

hardware: 1. physical equipment as opposed to programs, procedures, rules, and associated documentation; 2. the generic term dealing with physical items as distinguished from its capability or function such as equipment, tools, implements, instruments, devices, sets, fittings, trimmings, assemblies, subassemblies, components, and parts. Note: Hardware is often used in regard to the stage of development, as in the passage of a device or component from the design stage into the hardware stage as the finished object. [After JP1] 3. in data automation, the physical equipment or devices forming a computer and peripheral components. [JP1]

hertz (Hz): 1. the SI unit of frequency, equal to one cycle per second. Note: A periodic phenomenon that has a period of one second has a frequency of one hertz. 2. a unit of frequency which is equivalent to one cycle per second. [NTIA]

hot swap: removal and replacement of a board or other field replaceable unit while the host system is providing service (i.e., powered ON and operating)

icon: a small, pictorial representation of an application function, idea, or concept used in a label to represent commands, files, or options.

illuminants D (CIE): CIE Standard Illuminants for daylight, based on actual spectral measurements of daylight; D65 with a correlated color temperature of 6504(K is most commonly used to describe the color “white”

indicator: a lamp used to show visually (as by change of color) the status of the board, field replaceable unit, or enclosure (e.g., a light-emitting diode (LED)

Ishihara Test for Color Blindness: a test for determining color blindness by means of a series of cards each having colored dots that form one pattern to the normal eye and a different pattern to the eye that is color-blind. See the website at http://www.toledo-bend.com/colorblind/Ishihara.html for more information; Pronunciation: (ish" E-här' u)

SI, VITA 40-200x/D0.4 page 30 1/14/03

just noticeable difference (JND): the smallest amount of change (average) in physical value that is perceived by humans

label: 1. an identifier within or attached to a set of data elements. 2. one or more characters that (a) are within or attached to a set of data elements and (b) represent information about the set, including its identification. 3. In communications, information within a message that is used to identify specific system parameters, such as the particular circuit with which the message is associated. Note: Messages that do not relate to call control should not contain a label. 4. In programming languages, an identifier that names a statement. 5. An identifier that indicates the sensitivity of the attached information. 6. For classified information, an identifier that indicates (a) the security level of the attached information or (b) the specific category in which the attached information belongs.

light-emitting diode (LED): a semiconductor device that emits visible light when an electric current passes through it; most LEDs emit monochromatic light at a single wavelength.

lightpipe: a glass or plastic part designed to convey light from one location to another; in indicator applications it is typically used to convey light from a hidden source to a visible location on a front panel

mean time to repair (MTTR): the total time it takes to perform actions carried out to restore a defective item to a specified condition (including tests, measurements, and adjustments made to remove or correct a fault) divided by the total number of corrective maintenance actions during a given period of time; the average amount of time needed to repair a failed unit.

nanometer (nm): a unit of length equal to a 10-9 meter, or one millionth of a millimeter. Wavelengths are measured in nanometers.

permitted state: an operational condition (e.g., ON, OFF) or behavior (e.g., SLOW BLINK, STEADY) of an indicator that is allowed under this standard

red: the color used in this standard to indicate that the component or system is out of service; nominally 650 nm in this standard with an acceptable range of 615-660 nm

service action: any action carried out to restore a defective item to a specified condition (including tests, measurements, and adjustments made to remove or correct a fault)

service error: any human error committed by a service person while performing a service action

service management facility: any console, service processor, hardwired logic that can control the components and processes of a system to facilitate a service action; service management facilities may be automatic or manual

solder side (also see component-side): the side of a printed circuit board opposite which the majority of the electronic components are mounted

standby: 1. in computer and communications systems operations, pertaining to a power-saving condition or status of operation of equipment that is ready for use but not in use. Note: An example of a standby condition is a radio station operating condition in which the operator can receive but is not transmitting. 2. pertaining to a dormant operating condition or state of a system or equipment that permits complete resumption of operation in a stable state within a short time. 3. pertaining to spare equipment that is placed in operation only when other, in-use equipment becomes inoperative. Note: Standby equipment is usually classified as (a) hot standby equipment, which is warmed up,

SI, VITA 40-200x/D0.4 page 31 1/14/03

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