Register Addressing for Modbus TCP/IP while using Access Variables
I assume, you are using AC800M/CI867 as Modbus Slave configuration.
The following examples show how to address Holding/Input register address 45 (decimal):
Just try to use different range for send and receive, since CI867 is slave, address definition usually will be done on slave devices.
Lets say 1 to 1000 for send data range,
2000 to 3000 for receive data range