Tunnel – Periodically obtaining readings from 5 electronic meters and sending them to a webserver using the ModBus RTU protocol

Scenario details:

• We have 5 electric meters with ModBus RTU protocol. These meters have a series of readings in their internal memory (e.g. cumulative consumption and average consumption) which should be read and sent to a Web server periodically
• Therefore every 15 minutes the MTX-Tunnel has to question the 5 meters to read the records via a serial port. The records to be read are for the cumulative consumption (record nº20) and for average consumption (record nº 21)
• After every reading MTX tunnel has to send the records to a web server via HTTP GET using a JSON object. However it must be able to store up to 1500 readings in flash memory in case there is a communication failure with the 2G/3G/4G so that it can send them when the connection is restored. For each meter, it will send a JSON frame where it indicates the Modbus address/ identifier of the meter that has been read
• You need to be able to access MTX-Tunnel at any moment to be able to read PLC records in real time as well as being able to write them and modify the PLC configuration records

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

Config.txt configuration file:

Details:

• The summary of this example is as follows: The modem will periodically read, every 15 minutes, two ModBus records from each counter and they will be sent to a web server via a JSON object (to the URL specified in the LOGGER_server parameter). In the event that the record cannot be sent (if there is no GPRS coverage or the server fails), it will store the data to memory in order to send it later on. With Telnet you can connect to the equipment directly in order to check/ change the PLC records in real time (for this, search for the AT^MTXTunnel=getmodbus and AT^MTXTUNNEL=setmodbus commands in this manual)
• A JSON object sent to a specified URL in LOGGER_server is encoded in the following manner for example:

{“IMEI”:353234028103206,”P”:”ID00001”,”TYPE”:”MODB”,”A”:1,”TS”:”20/04/13 08:31:44”,”V1”:23,”V2”:275}

This means that the web Server receives a JSON object with the modem’s IMEI (IMEI), the password field (P) which can be used to identify the computer if you do not want to use the IMEI, the counter’s modbus address (A) which distinguishes the counter that relates to the readings, the time stamp (TS) which indicates when the modbus data has been read by each counter and “V1”/”V2” which indicates the readings that have been taken.

• At the end of the manual you will find how to configure the internal microswitch to activate the RS485 bus of this modem model