Definition
Modbus is a simple, widely adopted industrial communication protocol (available in both serial and Ethernet variants) for exchanging register-based data between a master device (such as a PLC or SCADA system) and one or more slave devices (sensors, drives, meters). Its simplicity and long-standing adoption make it common across many manufacturers' equipment, even alongside newer protocols.
Key facts
- One of the oldest and most widely adopted industrial protocols, available in both serial and Ethernet (Modbus TCP) variants.
- Uses a simple master-slave (or client-server) model with register-based data addressing.
- Broad manufacturer support makes it a common lowest-common-denominator choice for connecting equipment from different vendors.
- Simpler and less feature-rich than newer protocols like OPC UA, but valued for its simplicity and near-universal support.
How does Modbus work in maintenance?
Modbus works on a master-slave model, where a master device (a PLC, SCADA system, or similar) requests specific register values from one or more slave devices, which respond with the requested data: a simple, well-understood pattern implemented in both serial (RS-232/485) and Ethernet (Modbus TCP) forms.
What does Modbus require?
Modbus is simpler and older than protocols like OPC UA, PROFINET, or EtherCAT, lacking some of their more advanced features (rich data typing, built-in security models, deterministic real-time performance) but benefiting from extremely broad support across manufacturers, making it a common baseline choice, especially for simpler devices or legacy integration.
FAQ
Frequently asked questions
What communication task does Modbus perform?
Modbus exchanges register-based data between a master device and one or more slave devices using a simple, widely supported protocol, available in both serial and Ethernet variants.
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