1. Protocol Foundation

ModBus is a master-slave communication protocol widely used in industrial automation.The protocol supports one master device communicating with up to 247 slave devices.Each slave device has a unique address ranging from 1 to 247.

2. Transmission Modes

2.1 ModBus RTU

• Uses binary data transmission over serial communication
• Implements CRC error checking for data reliability
• Requires continuous data transmission without character gaps
• Messages are separated by idle periods

2.2 ModBus ASCII

• Transmits data in ASCII format over serial communication
• Uses LRC for error checking
• Messages start with “:” and end with CR/LF
• Easier to read but less efficient

2.3 ModBus TCP

• Operates on Ethernet networks using port 502
• No checksum needed due to TCP/IP protection
• Compatible with standard Ethernet equipment

3. Function Codes

Yeaplink routers support common ModBus function codes:

• 01H: Read Coil Status
• 02H: Read Input Status
• 03H: Read Holding Registers
• 04H: Read Input Registers

4. Frame Structure

RTU Frame:

Address (1 byte) | Function (1 byte) | Data (N bytes) | CRC (2 bytes)

ASCII Frame:

: | Address (2 bytes) | Function (2 bytes) | Data (N bytes) | LRC (2 bytes) | CR LF

5. Implementation Benefits

Yeaplink ModBus solutions offer:

• High reliability in industrial environments
• Easy integration with existing systems
• Comprehensive technical support
• Regular firmware updates

6. Application Guidelines

For optimal performance:

• Match communication parameters correctly
• Set appropriate timeout values
• Plan data request cycles carefully
• Monitor network load regularly

In today’s rapidly evolving industrial landscape, Industrial Routers equipped with ModBus capabilities represent a critical intersection of traditional industrial protocols and modern networking technologies. These devices continue to serve as the foundation for reliable industrial communication, enabling seamless integration between legacy systems and Industry 4.0 initiatives.

As we move forward, the role of Industrial Routers in maintaining secure, efficient, and reliable industrial operations becomes increasingly vital, particularly in applications requiring real-time data exchange and remote monitoring capabilities. Their ability to support multiple protocols, combined with robust security features and proven reliability, makes them indispensable components in modern industrial automation systems.