Issue
CO2 sensors have been installed on the VAV boxes that have a 0-10 volt output, but the Xenta 102-AX is limited to reading 0-5 volt output using the Universal Inputs on the controller. If replacing the sensors would be too costly and time consuming, this is a viable option that will allow you to drop the voltage output on the CO2 sensor using 1000 ohm resistors.
Product Line
TAC Vista, EcoStruxure Building Operation
Environment
102-AX
Cause
CO2 sensors have been installed on the VAV boxes that have a 0-10 volt output but the 102-AX is limited to reading 0-5 volt output using the Universal Inputs on the controller.
Resolution
NOTE: It is recommended that the incorrect sensors be removed and replaced with new sensors that have the proper specifications to match the 102-AX capabilities. If the sensor replacement is not an option please follow the instructions below.
Please see the image below:
- You will need (2) 1000 ohm (1k) resistors to complete this conversion.
- Wire one resistor directly to the output wire of the CO2 sensor
- Land that resistor to U3 on the 102-AX
- Jump a second resistor from U3 over to M on the 102-AX
- Land the other output wire from your CO2 sensor on M with the jumped resistor
Also see Using a 4-20mA CO2 sensor with a Xenta 102-AX to configure the Xenta 102-AX to accept a 4-20mA CO2 sensor input on Universal Input 3.
