Modbus Protocol
Modbus is a serial communication protocol commonly used for connecting industrial electronic devices, supporting RTU, ASCII, and TCP variants.
What is Modbus?
Developed in 1979, Modbus has become a de facto standard in industry. It uses a master/slave (client/server) architecture where a single master initiates all transactions. It operates on a register-based model, simplifying data access and control.
How We Use It
- Industrial Device Communication: Enabling our custom sensors to talk to standard PLCs.
- Sensor Data Polling: Creating gateways that aggregate data from multiple slave devices.
- Actuator Control: Sending precise commands to motor drives and valves.
- PLC Integration: Ensuring newly designed hardware acts as a compliant Modbus slave node.
Technical Details
We implement both Modbus RTU (over RS485) and Modbus TCP (over Ethernet/Wi-Fi). Our firmware stacks handle the rigid timing requirements of Modbus RTU framing and CRC calculation to ensure data integrity. We map application data to the standard register types: discrete inputs (read-only binary), coils (read/write binary), input registers (read-only analog), and holding registers (read/write analog).