Tunnel – Data transmission by RS232 via SMS for the control of electronic equipment with proprietary protocols. Use of ALIAS to send nonprintable characters
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Scenario details:
- It is necessary to send a series of commands by SMS to an electronic team, so that it executes actions
- The communication with the electronic equipment is through a proprietary binary protocol and is done through an RS232 port at 9600.8, n, 1. Therefore, it is necessary to implement an SMS-RS232 gateway
- The user needs to be able to send two types of messages by SMS. The message “OPEN” sends via serial port of the modem to the electronic equipment the data frame {0x01} {0x02} OPE1 {0x03}. The message “CLOSE” causes the sending by the serial port of the modem to the electronic equipment the data frame {0x01} [0x02} OPE2 {0x03}. Where 0x01, 0x02 and 0x03 are binary characters (not printable), while OPE1 and OPE2 are alphanumeric characters
Solution: MTX-Tunnel firmware + MTX-Java-IoT/MTX-Java-T/MTX-Java-T2 
EXAMPLE of configuration (config.txt file) for the indicated scenario. Solution for quick communication via Socket TCP:
| Configuration | Observations |
| COMM_baudrate: 9600 COMM_bitsperchar: 8 COMM_autorts: off COMM_autocts: off COMM_stopbits: 1 COMM_parity: none SMS_allPhones: on SMS_sendIP: on SMS_ATEnabled: on SMS_ATResponse: on MTX_PIN: 0000 MTX_mode: none MTX_model: 199801145 SMS_alias1: OPEN>AT^MTXTUNNEL=RS232,0,<HEX>0102</HEX>OPE1<HEX>03</HEX> SMS_alias2: CLOSE>AT^MTXTUNNEL=RS232,0,<HEX>0102</HEX>OPE2<HEX>03</HEX> SMS_aliasResponse: result |
Serial port baud rate |
Details:
- When the modem receives an SMS message with the text “OPEN” the modem will send by its serial port the bytes 0x01 0x02 followed by the alphanumeric text OPE1 and ending with the 0x03 byte
- It is possible to put multiple sections with the <HEX> </ HEX> tags. Among them, all hexadecimal values must have 2 digits. That is, the value “1” should be written as “01”