We need to monitor 100 devices with the RS232 port (115200.8.N.1 and HW flow control) from a central control station using a GPRS link. This will be done with the MTX-Tunnel to act as a transparent serial GPRS tunnel.
MTX-4G-JAVA-T AUS or MTX-4G-JAVA-IoT AUS and MTX Tunnel Firmware.
Access to the RS232 remote devices at any time is mandatory. So the modem connected to the serial port device (which needs to be controlled) must remain permanently connected to the GPRS, waiting for a connection. Access to the modems must only be allowed for the IP coming from the PC Control (188.8.131.52) and also for a backup IP coming from the central office ADSL line, which is: 184.108.40.206.
In order to reduce costs, SIM cards use dynamic IP addressing. As we have a large number of modems, we will not use DynDNS. Instead, every time the MTX Tunnel sends the IP that it has been assigned (by the GSM operator) to a control centre. Every time a modem changes its IP address, the new IP must be sent to the control centre in order to report the change (IP 220.127.116.11 and port TCP 20000). This way, the PC control centre always knows the current IP of each modem.