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70
Commissioning
8.3.7
Data Exchange Operating Mode Application Example
In the "Data Exchange" operating mode, the I/O module monitors process data
exchange with the partner module. If the connection is interrupted for 200 ms or
more, it generates a diagnosis in the status byte. This monitoring only takes into
account if there is a connection between the I/O modules. As the user, you may
want to check if the application that accesses the fieldbus node of the opposite
side as a PLC application or via fieldbus has received the information sent.
You can easily implement this monitoring by reserving 3 bits in the data part of the
process image for transmission of status information. Use bits 0, 1 and 2 of the
first data byte, for example.
1.
Use bit 0 as the "ON" signal on both sides.
2.
Describe bit 0 in the process image (output) permanently with status 1.
3.
Check if the "ON" signal is displayed correctly in the process image (input).
No connection if the status is "0"
If the status is 0, there is no connection with the opposite side and all data bytes
of the process image (input) of the I/O module are invalid.
4.
Use bit 1 as the "toggle" bit to send data to the opposite side.
5.
Invert the sent "toggle" bit if you want to send new data.
6.
If you have already sent data, you can only send new data if the opposite
has acknowledged receipt. Use bit 2 as the "acknowledge" bit on both sides
to signal data receipt to the respective opposite side.
7.
Always invert the sent "acknowledge" bit if the received "toggle" bit has
changed.
Manual
Version 1.3.0
750-652/040-000 Serial Interface RS-232/RS-485 XTR
WAGO-I/O-SYSTEM 750 XTR
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