Siemens ST PCS 7 manual Profibus DP

© Siemens AG 2007

Communication

PROFIBUS DP

Introduction

■Application

The PROFIBUS DP fieldbus enables the SIMATIC PCS 7 auto- mation systems (controllers) to communicate with distributed I/Os from the ET 200 range (remote I/Os) as well as with field/process devices, CPUs/CPs and operator terminals that have a PROFIBUS DP interface. It is possible to route the PROFIBUS DP into Ex zone 1 by using a fieldbus isolating trans- former (RS 485-iS coupler) and the RS 485-iS transmission tech- nology. Connection of the intelligent, distributed field/process devices and operator terminals on PROFIBUS PA to the automa- tion system takes place likewise through PROFIBUS DP.

Depending on the type of automation system and the number of available slots, up to 4 PROFIBUS DP lines can be connected to

a SIMATIC PCS 7 automation system through internal interfaces in the CPU, and up to 10 PROFIBUS DP lines through additional CP 443-5 Extended communications processors. On a PROFIBUS DP line it is possible to operate up to 125 devices, and on a bus segment up to 31 devices with PROFIBUS DP in- terface (32 stations).

Electrical and optical transmission technologies offer many dif- ferent configuration options for PROFIBUS DP networks. Electri- cal networks can span up to approx. 10 km. With optical trans- mission systems, the total size of the network is governed primarily by the cycle times as a result of the almost loss-free transmission.

With SIMATIC PCS 7, PROFIBUS DP topologies are always im- plemented through the standard electrical PROFIBUS DP con- nection on the automation system in the form of electrical or mixed (electrical/optical) networks. In the case of mixed net- works, the transition between the two media is implemented by an optical link module (OLM). As regards communication be- tween the stations, there is no difference between electrical two- wire technology and fiber optic technology.

Electrical networks can be configured with a line or tree topol- ogy. Mixed electrical/optical networks with OLMs as routers can be configured with a line, ring or star topology.

■Technical specifications

	PROFIBUS DP
	Data transmission	RS 485	RS 485-iS	Fiber-optic
9	Transmission rate	9.6 kbit/s ... 12 Mbit/s	9.6 kbit/s ... 1.5 Mbit/s	9.6 kbit/s ... 12 Mbit/s
	Cable	2-wire shielded	2-wire shielded	Plastic as well as multi-mode and
				single-mode glass-fiber
	Type of protection		EEx(ib)
	Topology	Line, tree	Line	Ring, star, line
	Nodes per segment	32	32 1)	–
	Nodes per network (with	126	126	126
	repeater)

Cable length per segment depen- dent on transmission rate

1200 m at max. 93.75 kbit/s

1000 m at 187.5 kbit/s

400 m at 500 kbit/s

200 m at 1.5 Mbit/s

100 m at 12 Mbit/s

1000 m at 187.5 kbit/s1)	Max. 80 m (plastic)
400 m at 500 kbit/s1)	2-3 km (multi-mode glass-fiber)
200 m at 1.5 Mbit/s1)	>15 km at 12 Mbit/s (single-mode
	glass-fiber)

Repeater for signal refreshing	Max. 9	Max. 91)	Not relevant
with RS 485 networks

1)According to PROFIBUS installation guideline 2.262

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Siemens ST PCS 7 · November 2007