# BACnet/IP

> Connect HVAC controllers, chillers, air handling units, VAV boxes, lighting and meters with BACnet/IP and combine building data with energy management.

BACnet is the standard protocol of building automation. PLCGateway's BACnet/IP client finds devices with Who-Is / I-Am, reads their object list with names, and reads present values and other properties with ReadProperty or ReadPropertyMultiple.

Writing uses WriteProperty with a priority of the priority array, and a value can be relinquished again. Together with the HVAC symbols of the screen designer and the ISO 50001 energy management this makes PLCGateway a compact building management and energy monitoring system.

- **Driver id:** `bacnet_ip`
- **Connection:** UDP 47808 (0xBAC0)
- **Address browsing:** yes
- **Writing:** yes
- **Included in:** PLCGateway Connect, PLCGateway SCADA, PLCGateway Embedded

## What PLCGateway reads and writes

- Analog, binary and multistate inputs, outputs and values
- Object name, description, units, status flags, reliability
- Priority array and relinquish default
- Device object and any property by number
- Writing with a priority and relinquishing (null)
- Who-Is discovery and object list browsing

## Address examples

| Address | Meaning |
|---|---|
| `AI:1 · AO:2 · AV:10` | Analog input / output / value (present value) |
| `BI:3 · BO:4 · BV:7` | Binary objects |
| `MSV:1` | Multistate value |
| `AO:2@8` | Write with priority 8 |
| `AV:10.name · AI:1.units` | Object name / units |
| `DEV:1234.name` | Device object name |

## Controllers and devices

- [Building automation and energy meters](https://plcgateway.com/controllers/building-automation.md)

## Connect in a few steps

1. Add a BACnet/IP device and use Find devices to discover the controllers in the network.
2. Open the object list and select the points with their names.
3. Set the write priority for set points and schedules.
4. Draw air handling units, chillers and meters with the HVAC symbols and add them to energy management.

## Questions and answers

### Does PLCGateway find BACnet devices automatically?

Yes. Find devices sends Who-Is and lists the answering devices with their instance number and address.

### Is BACnet MS/TP supported?

Directly only BACnet/IP. MS/TP devices are reached through a BACnet router to BACnet/IP.

### How are priorities handled?

Each device has a default write priority, and a single address can carry its own priority, for example AO:2@8. Writing null relinquishes the value.

## Related protocols

- [Modbus TCP / RTU](https://plcgateway.com/protocols/modbus.md)
- [OPC UA client](https://plcgateway.com/protocols/opc-ua.md)
- [All protocols](https://plcgateway.com/protocols.md)

_Product and model names are trademarks of their owners. They are named only to show which equipment the drivers communicate with; PLCGateway is not affiliated with these companies._

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Source: https://plcgateway.com/protocols/bacnet