Setting Up Read and Write Services

In the channel settings, you can change the default methods of reading property values from other devices and writing to other devices' properties.

To modify the read and write settings:

  1. Open Workbench and in the Project Explorer pane, expand your project > Data Connectivity > BACnet > Channels.

  2. On the General tab in the Read and Write Settings section, select the desired option in Read Service Type.

    Option descriptions:

    • Automatic: Uses the best available service type that is supported by the device.
    • Confirmed COV (Change of Value) and Unconfirmed COV: Relate only to the PresentValue property.
    • Read Property Multiple: Allows reading the values of multiple properties at once if it is supported. If not, use Read Property.

  3. In Write Service Type, select the desired option, and then click Apply.

    The Automatic option uses Write Property Multiple if it is supported by the device, otherwise it uses Write Property.

  4. Edit the remaining values related to the read and write services as needed.

    • Re-Subscribe COV Period: The period after which this device repeats the request to be notified of any changes to the PresentValue properties on other devices.
    • Polling Rate: The frequency at which this device retrieves real-time data from other devices. The range is between 0 and 4,194,303 seconds.

    • Priority: A number between 1 and 16 that determines the importance of the messages sent by this device in comparison to messages from other devices. Some priority levels are pre-assigned, others are available for setting your own priorities. The default setting is 8.

      ClosedView details

    • Decimal Places: The default number of decimal places for real values.

      Select -1 to use the settings from the device properties.

  5. Click Apply and continue with setting up the next sections, History Settings and Alarm Settings.