Using The Modbus Protocol Library - Siemens SIMATIC S7-200 System Manual

Using the Modbus Protocol Library

The STEP 7--Micro/WIN Instruction Libraries make communicating to Modbus devices easier by
including pre-configured subroutines and interrupt routines that are specifically designed for
Modbus communications. With the Modbus Protocol Instructions, you can configure the S7-200 to
act as a Modbus master or slave device.
You find these instructions in the Libraries folder of the STEP 7--Micro/WIN instruction tree. When
you put a Modbus instruction in your program, one or more associated subroutines are
automatically added to your project.
Siemens Libraries are sold on a separate CD, STEP 7--Micro/WIN Add-On: Instruction Library,
with the order number 6ES7 830--2BC00--0YX0. After version 1.1 of the Siemens Library is
purchased and installed, any subsequent STEP 7--Micro/WIN V3.2x and V4.0 upgrade that you
install will also upgrade your libraries automatically at no additional cost (when library additions or
modifications are made).
In This Chapter
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Requirements for Using Modbus Protocol
Initialization and Execution Time for Modbus Protocol
Modbus Addressing
Using the Modbus Master Instructions
Using the Modbus Slave Instructions
Instructions for the Modbus Protocol
Advanced Topics
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
348
348
349
350
351
352
353
362
347