S7300 communication using terminal server

We are using S7 315-2 plc with a cp-341 module. The PLC is in slave mode and is communicating to the HOneywell terminal server. We have a Serial to Fiber MOCA Nport IA 5150 which is set up as terminal server and a Fiber to Ethernet IMC 101 switch.

I can communicate on the Analog Inputs but am getting a ModBus exception error when I try to communicate the Digital Inputs.
I am using memory area 001 to 192 for FC 02.

Thanks
Anand