Issue
A temperature input on one device is referenced in an external binding, e.g. a consumer value, in another (BACnet) device. The value on the consumer side is incorrect and seems to have been converted from Fahrenheit to Celsius although the units all show Fahrenheit.
Product Line
EcoStruxure Building Operation
Environment
- Building Operation Workstation
- Building Operation Automation Server (Premium)
- Building Operation Enterprise Server / Enterprise Central
- BACnet Device(s) supporting external binding (e.g. MP-X or IP-IO)
Cause
The probable cause is that the value of the temperature input is not configured to a specific unit. This means that the unit is decided by the electrical type of the thermistor. In most cases this is Temperature °C, which means that the values are stored in °C, and this is the value being transferred in the consumer binding.
If the measurement system in Workstation is set to United States Customary Units (US), the input value will be displayed in Fahrenheit (°F) and one might think that the unit of the temperature input value is also configured to Fahrenheit, when in reality it is in Celsius.
In this situation the value on the consumer side is in Celsius as it has no information about units. Furthermore, if the consumer value unit is configured to Fahrenheit, then we have the situation shown in the screenshot above.
Resolution
- Start by changing measurement system in Workstation to As configured in object. (Refer to the Webhelp for more information about how to do this.) By doing this the values will be displayed unconverted.
It is now clear that the temperature input in reality is in Celsius. - The next step is to configure the input unit to Fahrenheit. Open up Properties for the Temperature input and click the gear wheel next to Value to configure.
- Check the box to the left of Unit and click the button with the three dots to the right.
- Select °F and click Select
- Click OK to confirm the changes in both open windows.
Both the temperature input and the consumer value will now be displaying the correct value in Fahrenheit.
