IoT_Gateway_Modbus: A MQTT Gateway connecting Modbus RTU with MQTT Bridge of Google IoT Core

Note: This repository was an exploration with EcoPhi and Engineers without Borders Karlsruhe. Futher investigations are continoued elsewhere, this repository is discontinued.

Scope of this solution:

This software is a user-solution of an "IoT Gateway" for Modbus RTU.

The intitial reason for starting this solution was the need for a Gateway for Solar Microgrids. A monitoring system for microgrids can help NGOs and companies e.g. in Eastern Africa, to prove project success and also improves predictive and reliable maintainance. Using a small embedded Linux/Windows computer, e.g. a Raspberry PI, low-cost Modbus RTU sensors can be read and a cost-effective monitoring solution is possible.

As provided this solution offers:

• Cloud: Google IoT Core

  • deploying and changing Modbus configuration from the GCP.
  • Reliable connection using Python Paho MQTT Client
  • low data footprint in GSM szenarios: compression of multiple sensor measurements using gzip

• Modbus: Modbus RTU: RS232, RS485 via USB interface.

  • read sensor values from 5-10 Modbus RTU Slaves per second
  • schedule individual indivdual for each sensor and slave

• Cloud: Google IoT Core

  • deploying and changing Modbus configuration from the GCP.
  • Connection using Paho MQTT Client
  • low data usage: compression using gzip and multiple sensor measurement at once

• Modbus: Modbus RTU: RS232, RS485 over USB.

  • read 5-10 Modbus RTU Slaves per Second
  • schedule indivdual for every sensor
  • handling of all modbus

Documentation Software:

• For the software documentation and installation see: README_gateway_software.md
• For additional instructions for the installation on a Raspberry Pi, follow 01_installation_raspberry_pi.md.

Related software:

• other clouds platforms: this module is designed for the GCP and Google IoT Core, however would also work with other MQTT Bridges. For Azure IoT Edge, a Modbus Gateway module exists, AWS Greengrass

About:

Required Python 3.7.7 libaries that are not included and must be installed separatley with the requirements.txt:

• "schema" is licensed under MIT Licence; available here
• "PyJWT" MIT Licence, 2015 Jose Padilla; available here
• "paho-mqtt" is licensed under Eclipse Public License v1.0 / Eclipse Distribution License 1.0 ; available here
• "Modbus Test Kit" is licensed under LGPL Licence; available here
• "pyserial" is licensed under BSD-3-Clause (BSD Licence); available here

This code example works with google IoT Core and other MQTT Briges. However, this code it not affiated with products of Google or Google Cloud.