TapHome to Modbus RTU / ASCII / TCP

Supported Communication Layers

The system accommodates three distinct protocols:

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

Setup Process

Configuration involves three primary steps:

1. Navigate to Settings → Expose devices and select Add Interface. Choose Modbus RTU, Modbus ASCII, or Modbus TCP.

2. Define communication properties:

   • For Modbus RTU or ASCII: Configure Terminal (BUS 1, BUS 2 or BUS 3), Baud rate, Parity, Data bits, Stop bits
   • For Modbus TCP: Set TCP Port (IP Address is configured individually per device)

3. Add devices for exposure:

   • Each device displays a brief overview of how third-party systems can access them

Example: Switch Configuration

Using Modbus TCP for System Integration

Simply Modbus provides comprehensive protocol documentation. Multiple open-source libraries enable TapHome integration with external systems:

• NModbus4 - C# Modbus protocol implementation GitHub
• libmodbus - Cross-platform library for Linux, Mac OS X, FreeBSD, QNX, Windows GitHub
• pymodbus - Complete Python-based Modbus protocol GitHub
• digitalpetri/modbus - High-performance Java implementation GitHub
• goburrow/modbus - Go language fault-tolerant implementation GitHub
• node-modbus-tcp - NodeJS Modbus TCP/IP

Debugging Modbus RTU Connections

RS485 physical layer utilization enables parallel monitoring. Consider connecting a “standard USB to RS485 converter” to your PC for communication visibility during integration efforts.

Recommended tools:

• Standard USB to RS485 converter
• Terminal software for Windows