How to Configure DidiOne IA to convert ModBus RTU to Modbus TCP/IT

I am experiencing communication issue with converting Modbus RTU to Modbus TCP/IP by using DigiOne IA. The communication between DigiOne and Modbus TCP/IP Server destabilized multiply times per day. As a Modbus TCP/IP Server I use ABB HPG800 getaway Controller with ABB HGS software. I have done troubleshooting if TCP/IP network and can eliminated any malfunction on this side.
There is Configuration of Digig One.
Serial Network : Industrial Automation,Modbus Slave Network,Modbus RTU,38400Baud,8Bit,Noparity,1 stop bit.
Please if any one can tell what can be done wrong. Or reference to document how to set Industrial Automation on DigiOne

Most likely this is an IP or ARP issue. So the device talk fine, but as ARP cache ages & changes, you lose the TCP socket. So one side thinks it is connected, but the other does not agree.

This won’t have any relation to the ‘modbus’ settings. Try to reduce the idle time-out, so the DOIA ‘hangs up’ on the server if it doesn’t talk repeatedly. Also look at any TCP and DHCP timeouts, reducing them.