Dear Montu,
I need to communicate with Conzerv energy meter of EM6400 series. There are 17 numbers of meters connected in one link.

I am using CP341 as modbus master and Modbus RTU as modbus protocol. Necessary driver and license are already installed in PLC hardware. The setup and programming are working fine for other modbus slave devices (e.g. numerical relay 7SJ61, pull cord switch controller) but did not respond with EM6400 energy meter. FB8 and FB7 had been used in PLC programming.

Wiring is done according to RS485 2-wire half-duplex mode. I have used the factory set default settings of baudrate 9600, parity even and stop bit 1. Unique slave addresses are assigned to the respective meters. I have used fucntion code 03 to read holding register values. Register address reference is taken from standard manual which tally to the one attched in your thread.

In a test setup, I have run 'Modscan' simulator as modbus master in my laptop and connected to the bus but did not have any positive result although the same approach had worked fine for other slave devices. When any slave is addressed in the bus, I get a response frame, but bytes for 'slave id' and 'function code' are totally different from that in the master query.

You said that you had alreday established modbus communication with the said energy meters. Kindly let me know what steps did you follow.

Thanking you in advance.
Annoy Kumar Das