BACnet Explorer: Writing Device Object Identifiers
Short answer: Some BACnet devices allow the Device Object Identifier (device instance) to be changed by writing to the device’s object_identifier property using the BACnet WriteProperty service. If the device supports this operation, you can perform it directly in CAS BACnet Explorer (version v2.01aQ or later) after discovering the device.
Important: Not all devices support writing the Device Object Identifier over BACnet. Many devices require vendor configuration tools or physical switches, and will reject BACnet write attempts.
Overview
Most BACnet devices set the device object identifier using vendor configuration software or a physical switch on the device. A small (but growing) number of devices allow you to configure the device’s object identifier by writing to the device’s object_identifier property using the BACnet protocol.
The Device Object Identifier uniquely identifies a BACnet device instance on a BACnet network. If a device permits this value to be changed over BACnet, CAS BACnet Explorer can be used to perform the write operation and confirm the result.
How to Write to the Device Object Identifier
- Start CAS BACnet Explorer. Version v2.01aQ or later is required.
- Discover your device.
- Right-click the object_identifier property of the device and select Write property.
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Change the data value to your desired object identifier (device instance) and click the Send button.
If the Device Does Not Support This Operation
If the device does not support writing the Device Object Identifier over BACnet, you will receive a BACnet error response (the exact message varies by device and implementation).
Note: CAS BACnet Explorer version v2.01aQ or later is required.
Key Terms
- BACnet Device Object Identifier (Device Instance)
- object_identifier property
- WriteProperty service
- CAS BACnet Explorer write property workflow
- Device support is vendor- and model-specific
Frequently Asked Questions (FAQ)
Can all BACnet devices change their Device Object Identifier via BACnet?
No. Support for writing the Device Object Identifier is optional and device-specific. Many devices reject write attempts and require vendor tools or hardware switches to change the device instance.
What CAS BACnet Explorer version is required?
Writing to the Device Object Identifier requires CAS BACnet Explorer v2.01aQ or newer.
What happens if the device does not support this feature?
The device will return a BACnet error response indicating the write operation is not permitted or supported. The exact wording varies by device.
What property do I write to in CAS BACnet Explorer?
You write to the device’s object_identifier property (within the device object).
Why would an integrator change the Device Object Identifier?
Common reasons include standardizing device instances across a site, avoiding conflicts, or aligning device numbering with commissioning documentation—when the device supports changing it over BACnet.
CAS BACnet Explorer
Need a BACnet discovery and troubleshooting tool? CAS BACnet Explorer is used by integrators to discover devices, inspect objects and properties, and test BACnet services like WriteProperty.