BACnet

Tutorial video

Examples

How to start with BACnet

Before enabling device for the first time in bOS, it is recommended that you check all the settings described below.

Connection

Select the appropriate connection type. In usual setups, the default settings are already okay. You just have to select the serial port for MSTP. For PTP you have to enter all the details (serial port, baud and password).

Discovery

When bOS receives IAM response from any BACnet device for the first time, it will try to add it under the main BACnet node. These are the settings where you can define what happens after that.

• Retrieve Objects: If set to true, bOS will ask newly added device for list of BACnet objects. When you finalize your configuration, it is recommended that you set this to false, so that you do not have unnecessary nodes appearing in your configuration, when adding other BACnet devices to the network.
• Generated Node Names: This setting defines how BACnet object names are generated upon discovery. There are three options. Name is object name, ObjectIdentifier is a string containing information of object type and instance. It can also be set to Both.
• Enable Sorting: If set to true, bOS will sort BACnet object list by object type and instance upon discovery. If set to false, the BACnet objects will appear in the same order as bOS receives them.

Timing

Those are the settings for COV timing and cyclical reading. Which one bOS uses is controlled by the settings on BACnet objects. Some devices might not support COV and some support only a few slots. If that is the case, you can use cyclical reading, which sends read commands every x milliseconds (defined by Read Delay setting). It is recommended that you use COV if device supports it.

• Subscription Time: This is a time in minutes and it defines for how long the COV subscription is valid. When defined time runs out, bOS will resubscribe. By BACnet standard, devices should support at least 8 hours long COV subscriptions. This is why the default value is 480 minutes. Some devices might not keep the 8 hours COV subscription. That is on you to figure out what works best for particular device and network.
• Read Delay: In case you are using cyclical reading, this is a delay in milliseconds between each read command. For example, if you have 10 objects to read and read delay is set to 250 ms, it will read each object every 2,5 seconds.

Functions Tab

There is one function called Send WhoIs. By using it, bOS will send WHO-IS broadcast to the network. BACnet devices that received this message shall respond by sending I-AM.