Tunnel – Serial 4G-UDP Tunnel. MTX configured as Client/Server UDP connected permanently to 4G and using a SIM card with a fixed IP address

Scenario details:

• We have 3 devices with an RS232 port (configured as 115200, 8, N, 1 and HW flow control) and they need to be monitored from a PC which is located in a Central Control station with Internet access
• It is important to have access to the RS232 devices at all times; therefore the modem is connected to the serial port device and must remain connected to 4G at all times
• The used protocol is not going to be orientated to the (TCP) connection because we want to use UDP for communications. The MTX Tunnel will be waiting for data packets on the UDP 20010 port sent from the Central Control PC. Every time a packet is received, it will be retransmitted by the serial port. Similarly the data packets received by MTX through the RS232 serial port will be retransmitted to the Control PC via UDP using the UDP 20011 port
• SIM cards with fixed IP addressing will be used. The Control PC IP is fixed but in anticipation of possible future changes, the DNS “oficina.domino.com” will be used instead of their IP address. Then the MTX Tunnel must resolve the DNS

Solution: MTX-Tunnel firmware + MTX-Java-IoT/MTX-Java-T/MTX-Java-T2

Config.txt configuration file:

Configuration

Observations

COMM_baudrate: 115200 COMM_bitsperchar: 8 COMM_autocts: on COMM_autorts: on COMM_stopbits: 1 COMM_parity: none GPRS_apn: internetestatico.movistar.es GPRS_login: MOVISTAR GPRS_password: MOVISTAR GPRS_DNS: 8.8.8.8 GPRS_timeout: 0 MTX_PIN: 0000 MTX_model: MTX-4G-Java-T MTX_mode: udp MTX_urc: off UDP_IP: oficina.dominio.com UDP_localPort: 20010 UDP_remotePort: 20011 FIREWALL_enabled: off

Serial port baud rate 8 bit data CTS hardware control enabled RTS hardware control enabled 1 stop bit No parity GPRS APN from your network operator GPRS Login GPRS Password DNS server IP address MTX-Tunnel is always GPRS connected If SIM card has no PIN security, use 0000 value MTX-Terminal modem model used UDP mode URC messages will not be sent Public IP address form central server Local port waiting for incoming connections UDP server port waiting for incoming connections Any incoming connection form any IP is allowed

Details:

• Remember that it is necessary to configure the router in the PC server location to use NAT with the UDP port, NOT the TCP port