Siemens Welding System ST PCS 7 Manual De Usuario

PROFIBUS PA

Siemens ST PCS 7 · November 2007

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Basic PROFIBUS PA design versions when using the DP/PA link as the 

router

Basic PROFIBUS PA design versions are presented at this point. 

In these configuration examples, DP/PA links are used in each 

case as the DP/PA router. Up to 5 DP/PA couplers can be oper-

ated in a DP/PA link. Mixed configurations (e.g. line and ring on 

one link) are also possible. The DP/PA router can also be imple-

mented with a DP/PA coupler. In this case, the PROFIBUS DP 

connection is directly on the coupler instead of per interface 

module.

In this design version, each PROFIBUS PA line is linked with one 

DP/PA coupler of a DP/PA router. Depending on the operating 

environment, you can use either the FDC 157-0 DP/PA coupler 

(up to Ex zone 2) or the Ex [i] DP/PA coupler (up to Ex zone 1). 

The DP/PA router can be connected to a single or redundant 

PROFIBUS DP.

The active field splitter (AFS) connects a PROFIBUS PA line with 

two FDC 157-0 DP/PA couplers of a DP/PA router. This router is 

operable on a single or redundant PROFIBUS DP. The AFS 

switches the PROFIBUS PA line to the active one of the two re-

dundant couplers. 
Flexible Modular Redundancy is possible at the device level by 

grouping individual devices in different PROFIBUS PA lines. 

Only one PROFIBUS PA line can be configured with coupler re-

dundancy on each DP/PA router. A PROFIBUS PA ring cannot 

then be operated on this router.

Active field distributors (AFD) integrate PROFIBUS PA field 

devices via 4 short-circuit proof spur line connections into 

a PROFIBUS PA ring with automatic bus termination. The 

PROFIBUS PA ring is connected to two FDC 157-0 DP/PA cou-

plers of a DP/PA router. The DP/PA router can be operated on a 

single or redundant PROFIBUS DP. Up to 8 AFDs can be config-

ured per ring.
Flexible Modular Redundancy is possible at the device level by 

grouping individual devices on different AFDs. Only one ring can 

be configured on each DP/PA router. A PROFIBUS PA line with 

coupler redundancy cannot then be operated on this router.
The following limits must be observed for a PROFIBUS PA ring 

with respect to the configuration with PROFIBUS PA devices:
• Max. 31 PROFIBUS-PA devices
• Max. current consumption of all PROFIBUS-PA devices: 1 A
Particular advantages of the ring architecture:
• High availability 
• Transparent redundancy management of the intelligent 

FDC 157-0 DP/PA couplers for the higher-level system

• Active bus terminations for automatic bus termination in the 

FDC 157-0 DP/PA couplers and the AFDs permit: 

- Automatic, bumpless isolation of defective sub-segments in 

event of short-circuit or wire breakage

- Changing of the ring configuration and the instrumentation 

during operation, including addition or removal of ring seg-

ments

• Safety-related and fault-tolerant applications with low device 

and cabling overheads

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PROFIBUS PA

PROFIBUS PA

PROFIBUS PA

PROFIBUS DP

Active field
splitter

Active field distributors

with redundant DP/PA couplers

with redundant DP/PA couplers

Direct fieldbus interfacing

Data transmission

MBP

Transmission rate

31.25 Mbit/s

Cable

2-wire shielded

Type of protection

EEx(ia/ib)

Topology

Line, tree, ring

PA devices per segment/coupler

31

PA devices per DP/PA link

64

Cable length per segment depen-

dent on transmission rate

1900 m: standard

1900 m: EEx(ib)

1000 m: EEx(ia)

© Siemens AG 2007