We need to monitor remote ModBus RTU devices with the RS485 port from a central Server which has a software application to control ModBus TCP. MTX-Tunnel will create a ModBus TCP/ModBus RTU GPRS gateway.
MTX-4G-JAVA-IOT AUS or MTX-4G-JAVA-IoT AUS modems + MTX-Tunnel firmware
ModBus remote devices to be available at all times, so the modem connected to those devices is permanently connected be IP waiting for incoming requests to the ModBus TCP port number 502.
SIM cards provisioned with fixed IP addressing will be used, but we could also use dynamic IP addresses and DynDNS or our own DNS server in the same way.