bus physics & wiring date 09/06/00, page 1 bus physics & wiring s profibus...

Bus Physics & WiringDate 09/06/00,

Bus Physics & Wiring

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PROFIBUS wiring/installation can be done with:

Copper

Fiber optic

Infrared & RF components



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PROFIBUS is based on RS485...

Network consists of RS485 segments

Proper installation

required



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PROFIBUS Segments

Connected via repeaters

New segment when maximum length or

number of devices per segment is reached



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PROFIBUS Segments - Repeater

Segment 2

Segment 1

Isolation

Segment 1



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PROFIBUS - Segment & Network Length

1001001002004001,0001,0001,0001,000

4,000

2,000

10,000

1,0001,0001,000

10,00010,00010,000

0

2,000

4,000

6,000

8,000

10,000

12,000

9.6 19.2 93.75 187.5 500 1,500 3,000 6,000 12,000 [kbaud]

Network [m]

Segment [m]

up to 9

in a rowup to

9

in a row



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PROFIBUS Segments - Nodes/Devices

Up to 126 addressable nodes per network

Up to 32 devices per segment

RepeaterPROFIBUSNodes (e.g. I/O)

Optical LinkModules(OLMs)

! No PROFIBUS Address !

! No PROFIBUS Address !

What counts as “device”?



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PROFIBUS Segments - Example

Address #0 Address #30 Address #31 Address #60

Address #90 Address #61Address #120 Address #91

Address #121 Address #125= Repeater

= OLM

No Address

No AddressNo Address

No Address

Up to 126 addressable nodes per network

Up to 32 devices per

segment



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Installation

Shielding & Grounding

Drop Lines

Termination

Cable Distances



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Installation - Shielding & Grounding

Improves EMC behavior

Provides a low impedance (short) return path for noise and current

Reduces the emission from the bus

!!!Shield is not always connected to

protective GND within the devices; therefore, make sure the cable shield will be connected to GND before it enters or

leaves the cabinet!!!

!!!Shield is not always connected to

protective GND within the devices; therefore, make sure the cable shield will be connected to GND before it enters or

leaves the cabinet!!!



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Installation - Cable Distances

CableCategory

II

>= 20 cm

>= 10 cm >= 10 cm

>= 50 cm

>= 50 cm

>= 50 cm

CableCategory

I

CableCategory

III

CableCategory

IV



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Installation - Cable... (continued) Category I:

LAN cables (e.g. Ethernet) Other communication cables

Category II: Shielded and unshielded cables for DC voltages > 60V and <= 400 V Shielded and unshielded cables for AC voltages > 25V and <= 400 V

Category III: Shielded and unshielded cables for DC and AC voltages > 400 V

Category IV: Signal cables of categories I - III at risk from direct lightning strikes,

e.g., connections between components in different buildings



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Installation - T-Connections (Drop/Stub/Spur)

Every branch or drop directly from the cable

Stubs to devices cause reflections (additional capacitance)

Repeaters are not spur-lines

RS485

(A)

(B)

Internal to device

Between device and trunk line

DeviceRS485

Device

! Manufacturer !

! Manufacturer !



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Installation - T-Connections (Drop/Stub/Spur)

100

0006.62033

500 500

0

50

100

150

200

250

300

350

400

450

500

550

600

9.6 19.2 93.75 187.5 500 1,500 3,000 6,000 12,000 [kbaud]

Allowed Length [m]

For Drops above

187.5kBaud:

use Bus Terminals or

RepeatersFor D

rops above

187.5kBaud:

use Bus Terminals or

Repeaters

Although stub lines can theoretically be tolerated at thelower baud rates, the recommendation is to avoid the use

of stub lines altogether.

Although stub lines can theoretically be tolerated at thelower baud rates, the recommendation is to avoid the use

of stub lines altogether.



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Installation - Termination

Termination for each segment at BOTH ends

Termination works ONLY when supplied with power

Via

ConnectorVia

Connector Via Active

Terminatio

n Box

Via Active

Terminatio

n Box

Via integrated

DIP Switches

Via integrated

DIP Switches



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Installation - Termination: Example

OLM OLM OLM

Repeater



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Wiring - Easy, when you use the right tools...



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4x

3. Insert the end of the cable into the stripper using your left index finger as a limit stop to ensure the correct length is inserted.

1. How to hold the insulationstripper in your right hand.

2. Match up the cable end with the template so that your left index finger is against the end surface of the tool.

6. With the clamp still closed,pull the stripper off the end ofthe cable.

4. Clamp the cable firmly in the stripper.

5. Rotate the stripper aroundthe cable 4 times in thedirection of the arrow.



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9. After removing the insulationfrom the cores, the cable canbe fitted into the PB connector.

7. The removed insulationremains in the stripper. Afterreleasing the clamp, theremnants can be removed.

8. Pull the protective foil off thecores.

green wire A

red wire B



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Copper is not the End of the Road...

Plastic, PCF and glass fiber optic available

Plastic - 50m between 2 Optical Link Modules (OLM)

PCF - 300m between 2 OLMs

Glass - up to 15km between 2 OLMs

Connections via modules or integrated interface

When is Fiber Optic the Choice?

Noise immunity & independence from potential differences

Cover longer distances

Line, ring and star configuration possible

Media redundancy



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Fiber Optic - Optical Link Modules (OLM)

OLM

PROFIBUS FO - Glass, PCF or Plastic



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Fiber Optic - Integrated FO Interface

= Optical Bus Terminal (OBT)

PROFIBUS FO - PCF or Plastic



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More Options... Infrared Components

Wireless linking of devices (up to 15m)

Communication with moving devices

Communication with changing devices

Noise immune

Ground independent

More Options... RF Technology

http://www.micro-control.no

http://www.akerstroms.no

bus physics & wiring date 09/06/00, page 1 bus physics & wiring s profibus...

Documents

bus physics

bus terminals

segment slide

profibus address

s profibus wiringinstallation

s installation t

cable shield

row slide