Tunnel – Control of the relays, digital outputs, digital inputs and 0-10V/4-20mA analog inputs of an MTX modem from a SCADA system using the MODBUS TCP protocol.

Scenario details:

• It is necessary to control 1 relay, 4 digital outputs (also connected to relays), 4 dry contact inputs and 2 analog inputs (one 0-10V type and another 4-20mA) located in a remote location
• Communication must be done from a SCADA system using Modbus TCP protocol
• For simplicity it is intended to use SIM cards with a public IP address
• The modem must be remotely configurable via SMS, Telnet and even Modbus

Solution: MTX-Tunnel firmware + MTX-IoT [4-S-N-N]-STD-P

Configuration example (config.txt file) for the indicated scenario:

Configuration

Observations

GPRS_apn: movistar.es GPRS_login: MOVISTAR GPRS_password: MOVISTAR GPRS_timeout: 0 MTX_pin: 0000 MTX_model: 199802407 MTX_ping: 35 MTX_pingIP: 8.8.8.8 MODBUSTCP_enabled: on MODBUSTCP_port: 502 MODBUSTCP_password: ABCD SMS_allPhones: on SMS_sendIP: on SMS_ATEnabled: on SMS_allPhones: on FIREWALL_enabled: off TELNET_enabled: on TELNET_login: user TELNET_password: 1234 TELNET_port: 20023 GPIO_mode0: input GPIO_config0: normal GPIO_mode1: input GPIO_config1: normal GPIO_mode2: input GPIO_config2: normal GPIO_mode3: input GPIO_config3: normal GPIO_mode4: input GPIO_config4: normal GPIO_mode5: input GPIO_config5: normal GPIO_mode6: input GPIO_config6: normal GPIO_mode7: input GPIO_config7: normal GPIO_mode8: input GPIO_config8: normal ADC_mode0: voltage ADC_config0: normal ADC_mode1: voltage ADC_config1: normal

GPRS APN provided by GSM operator GPRS Login GPRS Password Modem is permanently connected to GPRS PIN if it has one Device model Every 35 minutes PING check Google IP (f.e.) to ping Google IP (f.e.) to ping Reset if no registry on GSM network in 1800 secs. Time synch protocol IP by SMS authorized IP by SMS authorized AT by SMS allowed SMS AT responses activated Firewall status Telnet status Telnet login Telnet password Telnet port GPIO0 configured as an input GPIO0 normal configuration GPIO1 configured as an input GPIO1 normal configuration GPIO2 configured as an input GPIO2 normal configuration GPIO3 configured as an input GPIO3 normal configuration GPIO4 configured as an input GPIO4 normal configuration GPIO5 configured as an input GPIO5 normal configuration GPIO6 configured as an input GPIO6 normal configuration GPIO7 configured as an input GPIO7 normal configuration GPIO8 configured as an input GPIO8 normal configuration ADC0 as voltage input ADC0 normal configuration ADC0 as voltage input ADC1 normal configuration

Details:

• For simplicity, in this example the firewall has not been used, but remember that it has the FIREWALL_ parameters that could be used for greater communications security, allowing only communication with the Titan router from the public IP address of Scada.
• Remember that in the tables in Annex A of this manual you will find a table with the I / O of each modem model. Next to them you will find the modbus addresses of each one. For example, from the example model:

ID	@MODBUS	READING COMMAND	WRITING COMMAND
GPIO0	1	0x03	0x10
GPIO1	2	0x03	0x10
GPIO2	3	0x03	0x10
GPIO3	4	0x03	0x10
GPIO4	5	0x03	0x10
GPIO5	6	0x03	0x10
GPIO6	7	0x03	0x10
GPIO7	8	0x03	0x10
GPIO8 (relé)	9	0x03	0x10
ADC1	11	0x03	–
ADC2	12	0x03	–

• If you want to activate / deactivate via GPbus a GPIO configured in the config.txt as output, you must write a “0” or a “1” in the associated modbus register (@Modbus)