Set the range of a Xenta 102-AX CO2 sensor

[Product_Support]

Issue

A Xenta 102-AX accepts a 0-5V input on all external inputs. If Universal Input 3 is designated as CO₂, the range of the input needs to match the range of the sensor.

Product Line

EcoStruxure Building Operation, TAC Vista

Environment

• Xenta 102-AX
• Universal Input 3
• CO₂ sensor

Cause

The default setting (a gain of 1/1) results in

• 0V = 0ppm
• 5V = 1023ppm

(1023 is a resolution of the onboard analog to digital converter.)

Resolution

Refer to page 3-66 of the TAC Xenta 102-AX Software & Hardware Manual for more detail.

1. Calculate the required gain for the range of the CO₂ sensor.
   1. Ensure the sensor outputs a 0-5V signal.
   2. Note the CO₂ level at 5V. In this example, 2000ppm.
   3. Divide the maximum CO₂ reading by the analog to digital converter bit resolution (1023).
   4. Multiply the result by 1000.
   5. (2000 / 1023) * 1000 = 1955
2. Locate the value for Universal Input 3 SCPTgain. There are four locations to alter this value:
   1. Xenta 102-AX Plug-in
      Go to the Browser Tab > Xenta102AX > UnivIn3 Sense > SCPTgain > multiplier. Over on the right, enter in 1955/1000 and hit Set Value.
   2. LonMaker or LNS browser
      Open the browser window by right clicking on the 102-AX in the drawing and selecting Browser. Look in the Functional Block column for UnivIn3Sense. In that category is a point called SCPTgain. Click on it and then enter up top 1955/1000. Hit the red down arrow to download the value to the device. Enable monitoring on the nvoCO2sensor value or reopen the browser to view the new CO₂ value.
   3. Vista Workstation
      Go to the 102-AX.UnivIn3_Sense module and locate the SCPTgain point. Double click it. By Multiplier enter 1955 and by Divisor enter 1000.
   4. StruxureWare WorkStation
      Go to the 102-AX and click on UnivIn3Sense module and in the Variables tab locate the nciGainUIx point and expand it. For Multiplier, enter 1955 and save. For Divisor, enter 1000 and save.