I'm not familiar with that PLC but I can help with what you need to investigate.
A few PLCs support Modbus TCP 'scanning' where you just tell it what registers to read from the other device and set up a time interval. Most PLCs will require you to write some PLC programming that uses the instruction that they provide to do a Modbus register read. You will probably have to trigger this instruction at periodic intervals. You'll have to configure the instruction with the IP address of the device, the Modbus function code that you want to use, how many registers you want to read, the address of the first register, and probably some other information. The function code will probably be number 3 to read holding registers.
This requires studying 3 different things. The first is to gain an understanding of the Modbus protocol specification. It is a free download from the Modbus organization.
The next thing to study is the Modbus information for the device. You'll need to know how to set an IP address, a subnet, and perhaps a gateway address into it that your PLC can hit. You may have to set it to use the default Modbus TCP port 502. You'll need to study their Modbus 'register map'. I tend to say that Modbus register maps are the armpit of technical documentation because most of them are so poor.
The next step I would do is try to hit the device from a computer first before trying to hit it from your PLC. There are several software tools to do this. PM me if you would like some help in this area. The PLC class outline at CorsairHMI.com has some introductory Modbus information.
The next thing to study is the documentation for the Modbus read instruction(s) for your PLC.
When you get all this done you need to investigate the DNP side.....
