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
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.