20 lines
2.2 KiB
Plaintext
20 lines
2.2 KiB
Plaintext
You've described the situation perfectly. The protocol you're thinking of for HVAC and industrial controls is almost certainly **BACnet** or **Modbus**.
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Both are foundational protocols in building automation and industrial control, and they share the same conceptual space as CAN bus does for vehicles.
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First, to clarify your other point: **CAN bus** (Controller Area Network) is exactly what it's called. It's a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other's applications without a host computer.
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Here is a breakdown of the industrial/HVAC equivalents:
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| Protocol | Primary Use | Physical Layer | Key Concept (How it's like CAN bus) |
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| :--- | :--- | :--- | :--- |
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| **BACnet** | **Modern HVAC & Building Automation** | Runs on many layers, but commonly **RS-485** (a 2-wire bus, like CAN) or Ethernet (BACnet/IP). | This is the dominant, open standard for complex building control (chillers, air handlers, lighting, security). It allows devices from different manufacturers to interoperate in a single system. |
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| **Modbus** | **Industrial Controls & Simple HVAC** | Also commonly runs on **RS-485** (Modbus RTU) or Ethernet (Modbus TCP). | This is the de facto standard for industrial devices. It's simpler than BACnet and is a master-slave protocol (one device polls, others respond), but it serves the same purpose of connecting sensors, drives, and controllers on a shared network. |
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| **LonWorks** | Building, Home, and Industrial Automation | Twisted Pair (Free Topology) | A strong competitor to BACnet. It's a peer-to-peer protocol, which is conceptually very similar to CAN's multi-master design, where any device can initiate communication. |
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### Which one are you thinking of?
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* If you're thinking about a modern, large commercial building's entire automation system, the answer is **BACnet**.
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* If you're thinking about the most common, simple, and widespread protocol for connecting industrial sensors, VFDs (Variable Frequency Drives), and basic controllers, the answer is **Modbus**.
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Given the direct comparison to CAN bus as a system-wide network, **BACnet** is the most likely protocol you're trying to remember for the HVAC world. |