Modbus specificationsProtocol specification
Official Modbus Organization specifications: application protocol, serial line (RTU/ASCII) and Modbus TCP implementation guide.
- Manufacturer
- Modbus Organization
- Device type
- Protocol specification
Documentation · 3
Modbus Application Protocol Specification V1.1b3
Specification
The protocol itself: data model, function codes, request and response formats, exception codes.
Link verified 2026-10-01
Modbus over Serial Line — Specification and Implementation Guide V1.02
Specification
RTU and ASCII framing, timing (t1.5/t3.5), CRC and LRC calculation, RS-485 wiring, termination and biasing.
Link verified 2026-10-01
Modbus Messaging on TCP/IP — Implementation Guide V1.0b
Specification
MBAP header, TCP port 502, connection management and gateway (unit identifier) behaviour.
Link verified 2026-10-01
Diagnostics · 0
No reviewed diagnostic records for this family yet.