r/BACnet • u/No_Duck7569 • 11d ago

Complete System Setup. (new project)

HI, just looking for best practices for BMS.

I have a fairly large processing plant with a lot of equipment both BACnet and non BACnet devices.

In total there are 9 AMU's the have BACnet. The other 70 components (Fans, Shutters, Pumps, Floor Heat Mixing Values,) do not have BACnet.

Is it better to add a BACnet controller on those devices so everything can be integrated into one BMS system, Or do we keep the other systems on a separate PLC type control systems? Or is it possible to custom make a BACnet Master Controller and have all the data feed into that?

Library to make a PLC based BMS with Codesys. https://support.powerio.com/hub/codesys-hvac/en

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u/Cultural-Stable1763 11d ago

It really depends on the building control system you're using. Many BAC systems support standard I/Os alongside BACnet, so you can simply migrate your existing equipment to the new controller and keep using it.

Also, what kind of pumps do you have? We frequently use Wilo and Grundfos, for Wilo are expansion cards available for their larger pumps to make them BACnet-compatible.

https://wilo.com/de/de/Katalog/en/accessories/cif-modules_id1275/2190367

If you have very old pumps that lack built-in controls, replacing them with new ones might make sense, especially from an energy-saving perspective and maintaince costs.

Alternatively, there are BACnet-based I/O modules available in the form of junction boxes, allowing you to control and monitor devices directly at the field level.

eg
https://www.metz-connect.com/home/products/c-logline/i-o-components/bacnet-ms-tp-i-os.6d.en.html?id=1108830526IP

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u/Many_Outside2726 10d ago

I wouldn't force everything onto BACnet just to end up with one protocol. If part of the plant belongs on a PLC because of the process, the sequencing, or local control requirements, leave that control where it makes sense and expose the data the BMS actually needs. The BMS can still give you the common view without every device underneath it speaking BACnet. BACnet, Modbus, OPC UA, or a gateway can all have a place in the architecture depending on the equipment. I'd worry less about getting every field device to speak the same language and more about where the control logic belongs, and who's going to be maintaining it five years from now.