Tcp client + modbus gateway (tcp/rtu) for Fastrack


I’m looking for a firmware for telemetry application: Frastrack Supreme must connect to GPRS/3G/4G network, then start a TCP connection to a server, keep it connected (w keepalive packs) and reconnect every time connection drops.

Modbus gateway function is welcome too: it translate Modbus TCP from server side into modbus RTU to UART (serial port) and vice-versa.

Any idea where to find it?