Specifications

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PROFIBUS

System Overview

Data communication

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Siemens LV 1 · 2007

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Overview

Communication functions

The data communication (e.g. PROFIBUS FMS) is used to ex-

change data between automation devices or between an auto-

mation device and intelligent partners (PC, computer, etc.).

The following communication functions are available for this

purpose:

• PG/OP communication

Includes integrated communication functions by means of

which the SIMATIC automation systems can perform data

communication with HMI devices (e.g. TD/OP) and SIMATIC

PG (STEP 7). PG/OP communication is supported by MPI,

PROFIBUS and Industrial Ethernet networks.

• S7 routing

With the help of the S7 routing function it is possible to use PG

communication on an internetwork basis.

• S7 communication

This integrated communication function was optimized within

SIMATIC S7/C7. It also enables the connection of PCs and

workstations. The amount of useful data per job is 64 Kbyte.

S7 communication provides simple, efficient communication

services and a network-independent software interface for

MPI, PROFIBUS and Industrial Ethernet networks.

• S5-compatible communication (SEND/RECEIVE)

The SEND/RECEIVE interface (for PROFIBUS through FDL) is

optimized for communication between SIMATIC S5 and S7

controllers and thus enables migration from SIMATIC S5,

SIMATIC S7 controllers and PCs through PROFIBUS and

Industrial Ethernet.

• Standard communication

These are standardized protocols for data communication.

PROFIBUS FMS (Fieldbus Message Specification) is ideal for

the communication of different automation systems (e.g. PLC,

PC) from different manufacturers within a cell area with few

stations (max. 16). Communication with field devices with an

FMS interface is also possible. Using the FMS services READ,

WRITE and INFORMATION REPORT, one communication

partner can gain reading or writing access to another commu-

nication partner's variables through the variable index or vari-

able name or can transmit its own variable values to another

communication partner. Partial access to variable values is

supported. The communication is handled through acyclic

connections (master/master, master/slave), through acyclic

connections with slave initiative or through cyclic connections

(master/slave). With the INFORMATION REPORT it is possible

in addition to send a message to all stations on the network

with the help of a broadcast service. The FMS services IDEN-

TIFY (request for the partner's identification characteristics)

and STATUS (request for the partner's status) can be actuated

as well.

•OPC server

The basic principle behind OPC (OLE for Process Control) is

that OPC client applications communicate on a standardized,

open and hence vendor-independent interface with the OPC

server. IT communication can be implemented through the

OPC XML DA interface. Suitable OPC servers are included in

the scope of supply of the corresponding communication

software.