Function Block Modbuspn; Functionality Of The Fb - Siemens SIMATIC S7 Manual

6

Function Block MODBUSPN

6.1

Functionality of the FB

General
Information
Online-Help
MODBUS / TCP communication via the integrated PN interface of the CPU
2XV9450-1MB02; Manual edition 2.1
The function block MODBUSPN enables a communication between a PLC
with integrated PN interface and a partner which supports Open
MODBUS/TCP.
The function codes 1, 2, 3, 4, 5, 6, 15 and 16 are supported.
Depending on the parameterization, the FB can be operated either in client or
in server mode. In the server operating mode, the functionality multitasking in
the sense of the MODBUS specification is not implemented.
The block MODBUSPN calls the blocks MOD_CLI (FB104) and MOD_SERV
(FB105) internally. The block MOD_CLI comprises the function of Modbus
client, the block MOD_SERV executes the function of Modbus server and the
block TCP_COMM handles the connection management.
The blocks provide the following functions:
•
Connection and data handling by means of T blocks of the standard
library
•
Generation of MODBUS-specific telegram header before sending
•
Verification of the MODBUS-specific telegram header when receiving
•
Verification whether the memory areas requested by the client exist
•
Generation of exception telegrams when errors occur (only when S7
is in server mode)
•
Data transfer to and from the parameterized DB
•
Time monitoring of the data reception as well as connection
establishment and termination
•
Verification of the registration key
The SIMATIC Manager provides an online help for the function block
MODBUSPN. Mark the FB and press "F1" so that he online help is displayed.
It contains the main information on the FB.
Function Block MODBUSPN
6-1