Pm583 com1 rs485 communication problem
hi,i have two similar pm583 units.and I need to establish rs485 communication in com1 port.i was able to do the same for one unit using Com_ mod_mast block .And use the same program and settings for the second unit. But wasnt able to establish communication. And I found in the program enable bit for com_mod_mast block is not even get true please advice what are the things I need to check
Thanks in advance
Akhil
Thanks in advance
Akhil
Asked 1 year ago
Answers
1
Hi,
From your description it is not so clear for me what you are trying to do.
Just a few comments:
1. In case you want to use Modbus RTU connection between 2 PM583 using COM1 RS485 ports of each:
one of the PLC have to be a master and the other PLC - slave.
It is not possible to have 2 masters in one serial network segment.
2. In the master PLC you should use COM_MOD_MAST and read/write data from/to the slave.
At the input parameter EN of COM_MOD_MAST you have to provide (connect) pulses.
Each positive front at this input creates request from the master to read/write to the slave.
3. In the slave PLC you only have to declare variables where the master will read/write. The usual format is %MW0.x and %MX0.0.x ...
4. There are so many examples for that kind of connection in ABB site for AC500 and in this forum. You can look for details and working examples.
From your description it is not so clear for me what you are trying to do.
Just a few comments:
1. In case you want to use Modbus RTU connection between 2 PM583 using COM1 RS485 ports of each:
one of the PLC have to be a master and the other PLC - slave.
It is not possible to have 2 masters in one serial network segment.
2. In the master PLC you should use COM_MOD_MAST and read/write data from/to the slave.
At the input parameter EN of COM_MOD_MAST you have to provide (connect) pulses.
Each positive front at this input creates request from the master to read/write to the slave.
3. In the slave PLC you only have to declare variables where the master will read/write. The usual format is %MW0.x and %MX0.0.x ...
4. There are so many examples for that kind of connection in ABB site for AC500 and in this forum. You can look for details and working examples.
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