Modbus is a communication protocol used in automation and measurement technology to transmit measurement and process data between devices. Modbus RTU (Remote Terminal Unit) is a variant of this protocol based on binary serial transmission and typically used via interfaces such as RS-485 or RS-232.
Protocol Structure and Properties
The Modbus protocol follows a client/server structure (historically known as master/slave), in which a client sends requests and one or more servers respond to them. Modbus is considered a de facto standard because it is specified as an open protocol and is supported by many controllers, measurement devices, and field devices.
Modbus-RTU and Serial Transmission
With Modbus-RTU, the payload data is transmitted in a compact binary frame, which enables good data throughput compared to text-based variants. The transmitted data is not directly readable and must be converted by the analyzing software or the measurement system into a readable, scaled format (such as physical units).
Support for Modern Measuring Instruments
Many modern measurement and data logger devices support Modbus-RTU both as clients and as servers. This allows them, on the one hand, to read data from existing Modbus networks and, on the other hand, to make their own measurement values available to other systems via Modbus-RTU. Delphin measurement and data acquisition systems also offer a Modbus-RTU interface in numerous device series, allowing them to be flexibly integrated into existing automation and control systems.