Issue
Values from a third party BACnet device display the question mark character (?) instead of the correct engineering unit.
Product Line
EcoStruxure Building Operation
Environment
- Building Operation Enterprise/Automation Server
- Building Operation Workstation
- Third party BACnet device
Cause
The BACnet Standard revisions support a list of engineering units as enumerations, as shown in the extract below: -
| Enumeration | Unit | Unit type |
| 0 | square-meters | Area |
| 1 | square-feet | Area |
| 2 | milliamperes | Electrical |
| 3 | amperes | Electrical |
| …. | …. | …. |
The question mark (?) placeholder is used when Building Operation reads an unknown BACnet unit enumeration identifier. It is either a unit from a later revision of the standard, that has not been implemented by Building Operation yet, or it is a unit that is proprietary to the devices vendor.
Resolution
Based on different BACnet revisions, Building Operation can interpret the enumeration of units but proprietary units may not be handled correctly since these can vary by vendor, model and even the software version. Any lookup is specific to the vendor, model and software version.
The vendor of the third party equipment should be approached to modify their implementation according to the BACnet standard.
Additionally please see Points from an MPM display ?
