Siemens ST PCS 7 Ring architecture, Linear architecture with single coupler, Profibus PA, Mbp

© Siemens AG 2007

Communication

PROFIBUS PA

Introduction

■Design

Direct fieldbus interfacing

AS 414FH/

AS 417FH

DP/PA Link

PROFIBUS PA

DP		DP/PA Link
PROFIBUS	splitter
		PROFIBUS PA
		with redundant DP/PA couplers
	Active field

DP/PA Link

with redundant DP/PA couplers

Active field distributors

PROFIBUS PA

Ring architecture

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

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

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

9Basic 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.

Linear architecture with single coupler

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.

Linear architecture with redundant couplers

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.

■Technical specifications

PROFIBUS PA

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-	1900 m: standard
dent on transmission rate	1900 m: EEx(ib)
	1000 m: EEx(ia)

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Siemens ST PCS 7 · November 2007