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750-643 [MP-Bus Master Module]
Functional
description
WAGO-I/O-SYSTEM
750
I/O
Modules
More Information
Detailed references to the approvals are listed in the document "Overview
Approvals WAGO-I/O-SYSTEM 750", which you can find on the CD ROM
ELECTRONICC Tools and Docs (Item-No.: 0888-0412)
or in the internet under:
Documentation
WAGO-I/O-SYSTEM 750
System Description
2.1.1.6 Functional description
The MP-Bus master module is controlled by means of function modules in the
higher-level control application. The MP-Bus master module passes MP-Bus
commands and messages between the MP-Bus actuator and the function
module unchanged (tunneled through). In addition, macros for an expanded
command set are provided in the module. Commissioning is also carried out
exclusively via the associated function modules.
There are different ways of accessing and evaluating the process data
depending on whether the module is used in a fieldbus node with a
programmable fieldbus controller.
When a programmable fieldbus controller is used, several IEC 61131-3
function blocks are required for the MP-Bus master functions. The task of the
function blocks is to make access to the management and monitoring of MP-
Bus devices quick and convenient for the user. All function blocks are
available in the form of a function library.
The header bytes, the start byte and command byte, and the parameter content
to be transmitted must be made available to the module. The generation and
monitoring of the checksums is handled by the module. The module is
therefore independent of application-specific MP-Bus commands and does not
need to be modified on the software side when a new MP-Bus device with
new commands appears on the market.
Viewed from the module bus, the module can be looked upon as a pure slave,
exactly like an MP-Bus device. A response is initiated for every request to the
module received via the module bus. Whether this takes place immediately
after receipt or with a time delay depends on the transmitted request. The
exact requirement or task for the module is represented by the message code
(MSG_CODE).
