BACnet

Owned by Charles White, created
Jun 25, 2024
3 min read

Several systems are using BACnet in the FMS. These include PLCs, Ignition HMI, HVAC, and in some cases a combination. Both BACnet/IP and BACnet RSTP are present.

Systems Summary

  • PLC BACnet/IP communication is via a gateway and mainly facilitates control of the Primary Chillers in the Utility Building and PLC5.

  • The Alerton HVAC control system uses BACnet/IP and RSTP internally.

  • Ignition uses BACnet/IP to communicate with the primary chillers (read-only), AHU’s 02/03//04 (read-only), Alterton HVAC system, and the nLight Lighting system.

 

PLC

The BACnet gateway is a ProSoft unit set up via CSV file.

(ChrisF to add files and IP address access here)

 

Alerton HVAC

This system is a distributed native BACnet network with IP and RSTP devices. The main controllers are located in the outer ring Mezz Level. The overall architecture is divided between two main controllers labeled based on the CES equipment AHU03 and AHU04 and generally speaking, are mirror images of each other.

Hawaii Energy Systems is the install contractor and provided a Project Master object list which can be found here:

https://docs.google.com/spreadsheets/d/16UN7xYFndViSVL_ii4q_w_A0gtrs6UGiLsVQq8r4a9g/edit?gid=1148991108#gid=1148991108

There is a management server located in the server room FMS rack. This server is not required for the system to operate. It can be accessed using the following credentials:

user: dkist

PW: alerton1

 

Ignition

Ignition communicates with BACnet devices via the installed driver with a default write priority level of 8. This can be changed in the driver configuration settings.

Current device connections can be seen here: http://10.7.1.7:8088/web/config/opcua.devices?17

 

Tools

  • Yet Another Bacnet Explorer (YABE) is a free tool for writing, reading, basic trending, and discovery.

YABE can be downloaded here: https://sourceforge.net/projects/yetanotherbacnetexplorer/

You must be connected to the FMS network and have a static FMS IP address assigned to your computer. Ask an FMS lead for an IP address you can use.

  • There is also a simplistic BACnet tool built into the System Management HMI project. This doesn’t have all of the features YABE provides but does allow basic read, writing with priority, and relinquishing.

See below for instructions on how to use it.

 

 

 HMI BACnet tool Instructions

Open the System Management HMI project, BACnet Tools page.

  1. Select the Read or Write radio button

  2. Enter the device name. Typically this will match the device name in the Device Configuration in Ignition. For example, AHU01 18001.

  3. Select an Object Type from the dropdown box.

  4. Enter an Object ID. These can be found in the HVAC Project Master Google sheet for HVAC objects or you could use the tag browser in Igntion to find what you’re looking for.

  5. If you are writing, choose a priority and write value. These will be grayed out if you choose ‘Read’.

  6. If you are writing, selecting the Relinquish checkbox will send a None command and the position in the array for the selected priority will be relinquished.

  7. Once all selections are made press submit

    1. If reading the Present Value will be shown as well as the status of the priority array if the object has a priority property. Otherwise, it will be grayed out.

    2. If writing, the ‘Write Value’ will be written into the priority array according to the ‘Write Priority’ selection.

Notes:

  • The priorities are ordered from 1-16 with 1 being the highest. The value with the highest priority takes precedence. For example, if a binary output has a value of one with priority 8 and you write a 0 to priority 4, the output would change from on to off even though priority 8 is still on. If you relinquish priority 4, the next highest priority would take precedence, in this case 8, and the output would turn back on. This can be used to overnight values for testing or setting a default setting at a lower priority.

  • You will get an error if there is a mistake such as spelling or the object doesn’t exist in the device. Just hit reset and try again.

  • Keep in mind a value of 0 is not the same thing as relinquish. If the priority has no value (relinquished), it will be blank.

  • Not all objects have a priority property. In this case, whatever value was written last is accepted.

  • After writing a new value, you must click read and submit before seeing the change.

 

Be careful when writing as unintended consequences can occur.