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Tunnel – Use of an MTX as local data-logger modbus local, without SIM card or GPRS connections

Scenario details:

  • Over one month we intend to get the records of maximum and minimum temperatures in an industrial plant in order to perform a study on energy efficiency
  • We want the MTX-Tunnel to work as a local data-logger modbus; that is, it acts and reads data without needing to send them to any web server. The objective is that the MTX-Tunnel reads the data and stores them internally, like a “pen drive”. After one month, an operator will physically retrieve the MTX modem and will extract the data for further analysis
  • The device that will be used to read the temperature will be a temperature sensor modbus, specifically the model MTX-TEMP-IP65. The temperature is to be read every 30 minutes

Solution: MTX-65iRS485 modem + MTX-Tunnel software

EXAMPLE of settings (file config.txt) for such scenario:

Configuration Observations
COMM2_baudrate: 9600
COMM2_bitsperchar: 8
COMM2_autorts: off
COMM2_autocts: off
COMM2_stopbits: 1
COMM2_parity: none

GPRS_timeout: 10
MTX_PIN: 0000
MTX_mode: none
MTX_model: MTX65iRS485
MTX_portAux: modbusmaster
MTX_TPServer: null
MTX_ping: 0
MTX_configMode: reverse

LOGGER_enabled: on
LOGGER_registerSize: 100
LOGGER_numRegistersFlash: 1500

MODBUS_address: 49
MODBUS_start: 1
MODBUS_numwords: 1
MODBUS_period: 600
MODBUS_readCommand: 4
Serial port baud rate
Number of bits
No flow control
No flow control
1 stop bit
No parity
The modem will be connected
MTX-Tunnel mode
MTX modem model
AUXILIAR COM port used as master modbus
No time synchronization
Ping every 35 minutes without comms
So it works without SIM card
We enable the MTX Logger, to store the records
Register size
Maximum number of records in MTX
Sensor modbus address
Initial address to be read
N. of records read from the 1st sensor record
Every 10 minutes a reading is made
Sensors read with the modbus command 0x04


  • Notice the LOGGER_server parameter is not specified, as none will be used. Do not specify any in the configuration file so the MTX-Tunnel does not try to use it
  • For a proper working of the scenario, it is very important that parameters are in bold have the same value that in this example
  • Regarding the records numbers, it has been taken into account that temperature readings are made every 30 minutes, which implies 48 readings a day. 48 readings a day, 30 days (1 month) is 48 x 30 = 1440. This is the minimum number of records it needs to have to be able to register 30 days. For greater security we recommend 1500 records