Communication

3.2 Communication services

3.2Communication services

3.2.1Overview of communication services

Selecting the communication service

You need to decide on a communication service, based on functionality requirements. Your choice of communication service will have no effect on:

•the functionality available,

•whether an S7 connection is required or not, and

•the time of connecting.

The user interface can vary considerably (SFC, SFB, ...), and is also determined by the hardware used (SIMATIC CPU, PC, ...).

Overview of communication services

The table below provides an overview of communication services offered by the CPUs.

Table 3-2

Communication services of the CPUs

 

 

 

 

 

 

 

 

 

 

 

 

Communication service

Functionality

Time at which the S7

via MPI

via DP

via

via

 

 

 

connection is established ...

 

 

PtP

PN

PG communication

Commissioning, test,

From the PG, starting when

X

X

–

X

 

 

diagnostics

the service is being used

 

 

 

 

OP communication

Monitor and modify

via OP at POWER ON

X

X

–

X

S7 basic communication

Data exchange

is programmed at the blocks

X

–

–

–

 

 

 

(SFC parameters)

 

 

 

 

S7 communication

Data exchange in server

via active partner at POWER

Only in

Only in

–

X

 

 

and client mode:

ON.

server

server

 

 

 

 

Configuration of

 

mode

mode

 

 

 

 

communication required.

 

 

 

 

 

Global data

 

Cyclic data exchange (for

does not require an S7

X

–

–

–

communication

example, flag bits)

connection

 

 

 

 

Routing PG functions

for example testing,

from the PG, starting when the

X

X

–

X

(only for CPUs with

diagnostics on other

service is being used

 

 

 

 

DP or PN interface)

networks also

 

 

 

 

 

PtP communication

Data exchange via serial

does not require an S7

–

–

X

–

 

 

interface

connection

 

 

 

 

SNMP

 

Standard protocol for

does not require an S7

–

–

–

X

(Simple Network

network diagnostics and

connection

 

 

 

 

Management Protocol)

configuration

 

 

 

 

 

open communication by

Data exchange via

Does not require an S7

–

–

–

X

means of TCP/IP

Industrial Ethernet with

connection, is handled in the

 

 

 

 

 

 

TCP/IP protocol (by means

user program by means of

 

 

 

 

 

 

of loadable FBs)

loadable FBs

 

 

 

 

3-6

CPU 31xC and CPU 31x, Technical data

Manual, Edition 08/2004, A5E00105475-05

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Siemens S7-300 appendix Communication services, Overview of communication services, Selecting the communication service
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