way or module bus) for exception reports, and packs the excep-

tion reports having a common node destination. Packingplaces all exception reports for a destination (or multiple desti-nations) into one message (of variable length). The NIS moduleI-E96-610ASECTION 2 - DESCRIPTION AND OPERATION

INTRODUCTION

INFI-NET is a unidirectional, high-speed serial data highwaythat can be used by all INFI 90 modules. The INNIS01 NetworkInterface Slave Module (NIS) and the INICT01 INFI-NET toComputer Transfer Module make up the INICI01 INFI-NET toComputer Interface. The NIS module, INICT03 INFI-NET toComputer Transfer Module, and the IMMPI01 Multi-FunctionProcessor Interface Module make up the INICI03 INFI-NET toComputer Interface.

MODULE INTEGRITY

All INFI-NET communication modules have normal INFI 90security functions that insure module integrity. The modulehardware checks for illegal addresses and monitors themachine fault timer (MFT) and the I/O expander bus clock. If amodule detects an illegal address, it generates a bus error anddisplays an error code on the faceplate LEDs. If the micropro-cessor fails to reset the MFT timer, it expires. When this hap-pens, the communication module stops and the status LEDturns red. Module hardware also monitors the I/O expanderbus clock. If there is no clock signal, the module hardware gen-erates an interrupt.

INNIS01 NETWORK INTERFACE SLAVE MODULE

The NIS module serves as an I/O module to both the INICT01and INICT03 modules. While each computer interface uses dif-ferent INFI-NET communication modules, the NIS moduleoperates with each communication module in the same man-ner. This section provides an overview of INFI-NET communi-cation module operating theory.

Exception Reports

Each INFI 90 module establishes exception reporting parametersfor process inputs (points). Some examples of exception reportparameters are high and low alarm limits, minimum and maxi-mum report time intervals, and percent of change in span limits.When a point changes more than a given parameter, or an alarmstate changes, the module generates an exception report.

The computer transfer module polls modules (via the Control-INTRODUCTION 2 - 1

DESCRIPTION AND OPERATION sends this message to other INFI-NET nodes. This processreduces the number of transmissions required, and adjuststhe message size for maximum INFI-NET loop efficiency.

Exception reports can have data values in the following for-mats: Boolean, analog, digital and status report. Exceptionreports are time stamped to reflect their processing sequence.

The maximum and minimum report time parameters insurethat an exception report is generated for static or rapidlychanging data. The minimum report time parameter controlsthe quantity of exception reports a single rapidly changingpoint generates. The maximum report time parameter gener-ates a periodic exception report of data items that do notchange or change very slowly.

NOTE: If a point goes into or out of alarm, the time parameters areignored and an exception report is generated immediately.

Messages

The NIS module processes four different message types. Theyare broadcast, time synchronization, multicast, and NIS poll.

BROADCAST

The NIS module generates a broadcast message when sendinginformation to all system nodes. Typically, these messagesannounce changes in node status. Broadcast messagesinclude NODE ONLINE, NODE OFFLINE, NODE RESTART andNODE BUSY.

TIME SYNCHRONIZATION

The time synchronization message is a high priority broadcasttype of message. The NIS module services this message typeimmediately. Time synchronization provides a common systemtime base to be used for sequencing exception reports, access-ing trend data, and display on a system console.

MULTICAST

A message that contains data for multiple destinations is amulticast message. This message can have from one to 64destinations.

NIS POLL

The NIS poll message is a single destination message. The NISmodule uses this message type to poll the operational status ofanother node.

MESSAGE FORMAT

Messages exist as frames of information. Each frame consistsINNIS01 NETWORK INTERFACE SLAVE MODULE2 - 2 I-E96-610A

of a message control field that follows an information field. The

DESCRIPTION AND OPERATION

I-E96-610Ainformation field contains the message data. It can consist ofmultiple messages and vary in size to a maximum of 1,500bytes. The control field contains time of origination, sequence,source, size, circulation count, message type, destinations,and checksum value.

The NIS module increments the circulation count field of allincoming messages. When a message count field reaches 256,the next message is discarded. This is useful in keeping retryand spurious message traffic to a minimum. The NIS moduleuses the message type to determine how to process the mes-sage. The checksum and cyclic redundancy check code fieldsverify data integrity.

MESSAGE TRANSMISSION

Any NIS module can transmit a message at any time withoutregard to the activities of any other NIS module on the system.Each NIS module can transmit and receive messages simulta-neously. NIS module start-up or shutdown is local andrequires no interaction with other NIS modules on theINFI-NET loop. Each NIS module receives all incoming mes-sages and transmits a new stream of messages in a store andforward fashion to the next node. When there are no messagesfor the NIS module to transmit, the NIS module transmits flagcharacters (null packets) as the loop synchronizing conditionto keep the receivers in lock.

NIS Data Integrity

There are three methods the NIS module uses to insure dataintegrity. They are retry logic, node status table, and polling.

RETRY LOGIC

If on the first message transmission the NIS module does notreceive a positive or negative acknowledgment from the desti-nation node, it retransmits the message eleven times. If afterthis series of retries there is still no response, the destinationnode is marked off-line and the NIS module informs other com-munication modules of the negative acknowledgment.

NODE STATUS TABLE

The NIS module maintains an internal table of system widestatus's such as off-line and busy nodes. The NIS modulerelays node status changes to other communication modules.When the NIS module periodically polls nodes, it updates thistable accordingly.

POLLING

The NIS module uses the information in its status table forpolling purposes. As it scans the status table, it picks outINNIS01 NETWORK INTERFACE SLAVE MODULE 2 - 3

DESCRIPTION AND OPERATION destinations targeted for multicast messages that have beenmarked off-line or busy. After polling the destination, the NISmodule updates its table and forwards pertinent information toother communication modules.

INICT01 INFI-NET TO COMPUTER TRANSFER MODULE

The INICT01 INFI-NET to Computer Transfer Module (ICT) pro-vides the electronics needed to direct the operation of theINFI-NET to Computer Interface. It handles all communicationwith the host computer through a RS-232-C serial communi-cation port. It communicates directly with the NIS module overthe I/O expander bus. When communicating through theserial port, the ICT module can act as data communicationequipment (DCE) or data terminal equipment (DTE). The dip-shunt configuration on the termination unit (NTMF01) or mod-ule (NIMF01 or NIMF02) determines if this computer interfaceoperates as DTE or DCE.

The ICT module has enough memory that it can store up to10,000 point definitions (depending on point types). ICT mod-ule firmware enables the host computer to issue commands fordata acquisition, process monitoring and control, and systemfunctions (security, time and configuration control). The ICTmodule maintains the point table and interprets commandscoming from the host computer. Thus, it directs all interactionbetween the host computer and the INFI-NET system.

The ICT module receives data from INFI 90 modules and thensorts, organizes, and stores it in its database. The NIS modulereceives frames from the INFI-NET system and passes them onto the ICT module for processing. The ICT module then sortsthis incoming data, storing exception reports and incomingrequests until the host computer is ready for the data. Thisbuffering action allows the host computer to operate com-pletely asynchronously to the INFI-NET loop. When the host isready to process more data, it issues a command to the ICTmodule that forwards the data as a reply.

INICT03 INFI-NET TO COMPUTER TRANSFER MODULE

The INICT03 INFI-NET to Computer Transfer Module (ICT) alsoprovides the electronics needed to direct the operation of theINICI03 INFI-NET to Computer Interface. It handles all com-munication with the host computer through the IMMPI01Multi-Function Processor Interface Module (MPI) SCSI orRS-232-C communication ports. When communicatingthrough the RS-232-C serial port, the MPI module can act asdata communication equipment (DCE) or data terminal equip-ment (DTE). The jumper configuration on the termination unit(NTMP01) or termination module (NIMP01 or NIMP02)INICT01 INFI-NET TO COMPUTER TRANSFER MODULE2 - 4 I-E96-610A

DESCRIPTION AND OPERATION

I-E96-610Adetermines if this interface operates as DTE or DCE. It alsocommunicates directly with the NIS module over the I/Oexpander bus.

The ICT module has enough memory that it can store up to30,000 point definitions (depending on point types). ICT mod-ule firmware enables the host computer to issue commands fordata acquisition, process monitoring and control, and systemfunctions (security, time and configuration control). The ICTmodule maintains the point table and interprets commandscoming from the host computer. Thus, it directs all interactionbetween the host computer and the INFI-NET system.

The ICT module receives data from INFI 90 modules and thensorts, organizes and stores the data in a database. The NISmodule receives frames from the INFI-NET system and passesthem on to the ICT module for processing. The ICT modulethen sorts this incoming data, storing exception reports andincoming requests until the host computer is ready for thedata. This buffering action allows the host computer to operatecompletely asynchronously to the INFI-NET loop. When thehost computer is ready to process more data, it issues a com-mand to the ICT module that forwards the data as a reply.

The MPI module provides the ICT module with serial ports anda SCSI interface. It contains SCSI and RS-232-C I/O ports.

INFI-NET TO COMPUTER INTERFACE COMMANDS

The computer transfer modules receive a command from a hostcomputer, perform the desired action, and then reply to thehost computer. The computer interface uses over 80 com-mands for data acquisition, process monitoring and control,and system functions (security, time, configuration). Thesecommands fall into four basic command types: data acquisi-tion, configuration, process control, and system status.

Data Acquisition

The host computer uses the ESTABLISH POINT and ESTAB-LISH REPORT commands to establish a database in the ICTmodules. This database has the capacity for 10,000 points(INICI01) or 30,000 points (INICI03), depending on point types.The host computer has access to the ICT module databasethrough data acquisition commands. Any trend block config-ured in the system can be read through the TREND DATAPOLL command.INFI-NET TO COMPUTER INTERFACE COMMANDS 2 - 5

DESCRIPTION AND OPERATION Configuration

The computer interfaces can be used to download controlstrategy configurations to INFI 90 modules. Also, the TUNEBLOCK and READ BLOCK OUTPUT commands are used totune and monitor outputs.

Process Control

The command list provides process control abilities for the hostcomputer. The host computer is able to handle analog and dig-ital process requirements such as changing setpoints and con-trol outputs, supplying data values to INFI 90 module blocksas exception reports, controlling and setting digital remoteswitches and constants.

System Status

Time synchronization is a critical function of the computerinterfaces and part of overall status. It enables the host com-puter to set and display system time and date, and provides amechanism for relating the time stamp to system time anddate. The host computer is able to monitor individual modulestatuses and provide password protection.INFI-NET TO COMPUTER INTERFACE COMMANDS2 - 6 I-E96-610A

Document SummarySECTION 2 - DESCRIPTION AND OPERATIONINTRODUCTIONMODULE INTEGRITYINNIS01 NETWORK INTERFACE SLAVE MODULEException ReportsMessagesBroadcastTime SynchronizationMulticastNIS PollMessage FormatMessage Transmission

NIS Data IntegrityRetry LogicNode Status TablePolling

INICT01 INFI-NET TO COMPUTER TRANSFER MODULEINICT03 INFI-NET TO COMPUTER TRANSFER MODULEINFI-NET TO COMPUTER INTERFACE COMMANDSData AcquisitionConfigurationProcess ControlSystem Status