modbus tcp\ip addressing

I need to connect my pm554 eth CPU to OPC server, I'm using Kepserver. Can I connect to there using Modbus tcp\ip if I have provided an IP address to my CPU using a router? Also how I will address my input and output coils? I have configured as per Modbus addressing and while going to client connection is good a=but it doesn't read the values from the plc. Should I change or add something to my plc in communication?