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Expose TapHome devices via Modbus RTU / ASCII / TCP

Supported communication layers

  • Modbus RTU via RS485 (BUS 1, BUS 2, or BUS 3 terminals)
  • Modbus ASCII via RS485 (BUS 1, BUS 2, or BUS 3 terminals)
  • Modbus TCP (via ethernet, connecting to local IP address or VPN)

Setup

  1. Open Settings → Expose devices and select Add Interface. Select Modbus RTU, Modbus ASCII or Modbus TCP.
  2. Define communication properties
    1. Modbus RTU or ASCII: Terminal (BUS 1, BUS 2 or BUS 3), Baud rate, Parity, Data bits, Stop bits
    2. Modbus TCP: TCP Port. (IP Address is set specifically for every device)
  3. Add devices to be exposed
    Each device will show brief overview how to access them in 3rd party system
    Example: Switch:

Using Modbus TCP to connect to any other system

Simply Modbus is a great source if you are unfamiliar with the protocol. Using open source libraries for Modbus, you can connect TapHome installation with any other system that has possibility to develop a simple driver:

  • NModbus4 - C# implementation of the Modbus protocol (GitHub)
  • libmodbus - A Modbus library for Linux, Mac OS X, FreeBSD, QNX and Windows (GitHubhttp://libmodbus.org)
  • pymodbus - A full modbus protocol written in python (GitHub)
  • digitalpetri / modbus - High-performance, non-blocking, zero-buffer-copying Modbus for Java (GitHub)
  • goburrow / modbus - Fault-tolerant implementation of modbus protocol in Go (golang) (GitHub)
  • node-modbus-tcp - NodeJS Modbus TCP/IP (GitHub)

Debugging Modbus RTU connection

Modbus RTU is using RS485 physical layer. In order to speed up your integration, please consider parallel connection of RS485 USB converter to your PC in order to see communication.

Standard USB to RS485 converter: http://sk.farnell.com/ftdi/usb-rs485-we-1800-bt/cable-usb-rs485-serial-converter/dp/1740357

Terminal software for Windows: http://www.der-hammer.info/terminal/