Siemens SIMATIC OEM PP32, Equipment Manual

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2-13
OEM Push Button Panel Equipment Manual
Release 08/98
2.4 Coordinating the Push Button Panel and PLC
In the case of connection type MPI, so-called control and acknowledgment bits
are provided for the coordination between the Push Button Panel and PLC.
They are used for the following functions:
S
Detection of Push Button Panel startup by the S7 program
S
Analysis of Push Button Panel life bit by the S7 program
S
Polling error information in the S7 program
The control and acknowledgment bits are set in the first and second byte of the
configuring data block. In order to use the above mentioned functions, a con-
figuring data block must be created, as described in Chapter 2.3.1.
The first byte is reserved.
The figure below illustrates the structure of byte n+1. The individual bits are
described underneath the figure.
7 6 5 4 3 2 1 0
Address
n+1
Life bit
Start bit
Bit 0 Start bit:
1
= Push Button Panel has started up
The bit is set by the Push Button Panel on completion
of startup. You can reset the bit via the S7 program and
thus detect if the OP is restarted.
Bit 2 Life bit :
The life bit is set from 0 to 1 by the Push Button Panel.
You can cyclically reset the bit via the S7 program to
detect whether the connection to the Push Button Panel
still exists.
Introduction
Description
Byte n+1
Starting Up the Push Button Panel