OPC UA vs Modbus
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The Founder's Explanation (Teach Exactly This Way)
"Modbus is a box with only a number on it — you must keep a separate list to know what is inside. OPC UA is a parcel with a printed label — name, weight, contents, all on it. If you just want to move a few boxes, the number is fine. If many people must understand the parcel without asking you, the label wins."Teaching the Concept
The Numbered Box and the Labelled Parcel A box marked only 40001 tells you nothing without a separate list. A parcel with a printed label — name, unit, contents — explains itself to anyone. Modbus is the numbered box; OPC UA is the labelled parcel. Choose by whether meaning must travel with the value. Side by Side ``` MODBUS OPC UA register addresses named, typed objects manual map + scaling self-describing model no built-in security certificates + encryption simple, ubiquitous rich, structured, secure ``` Same Point, Two Worlds ``` MODBUS 40001 = 250 (engineer must know: x0.1 deg C) OPC UA SupplyWaterTemp = 25.0 deg C (name+type+unit) ``` Modbus gives you numbers; OPC UA gives you numbers that explain themselves — pick simplicity or structure.Related Topics
- What is Modbus and its history? — the simple register-based protocol
- Modbus to BACnet gateway explained — how a gateway translates protocols
- Browse all Protocols topics — more from this section of the EnSmart BMS Library
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