BEWATOR COTAG 4101-2, Installation Handbook, Page: 147 / 158

Fault finding
19-15
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RXD/ RXD on CONN4 of the Comms module should be
connected to TX/ TX on CONN2 of all the motherboards.
TXD/ TXD on the Comms module should be connected to
RX/ RX of all the motherboards.
•
Check that each Controller motherboard in the branch has a
unique address on SW1/SW2.
•
If you can’t get one or more Controllers to communicate after
checking all the above, remove the RS485 connectors from all
the motherboards except one, power up the Controller with the
Comms module in it and check that it can communicate with
just the one Controller. Reconnect the controllers one at a time
until you find the Controller which is not working. You will
probably find that the connections are reversed on a part of
the branch, or, it is possible that a single Controller is faulty.