Modbus RTU ---> GPRS Modbus transparent---> Internet ---> Domain ---> Wifi--->PDU.

I want to read Modbus registers remotely on the PDU side (remote client).

I have Modbus TCP client software on the PDU which shows successful connection but does not show register values? All my addresses are correct? Can someone please suggest what could be wrong?

 

You could try Wireshark and compare with the modbus spec. That should give you an immediate sign of what is wrong.

I am guessing that your device is using modbus RTU while your computer is using Modbus TCP/IP, and the format is slightly different.

 

Hello,

Are you sure that you have connections between PDU and Modbus RTU ?
Did you try ping the PDU from Modbus RTU or better telnet at port 502?

Regards,
Andrzej
www.modbus.pl