Two Point Calibration Routine - Johnson Controls - LIT-12012523 - Temperature Data Acquisition Module

Temperature Data Acquisition (TDA) Module Technical Bulletin
Product
Building Automation Systems > Databases and Data Servers > Temperature Data Acquisition Module
Document type
Installation Guide
Document number
LIT-12012523
Revision date
2021-03-30

About this task

A two point calibration may be required to correct input inaccuracies.

Procedure

  1. Connect a reference resistance (4,000 ohms ± 100 ppm: 3,000 ohms minimum, 10,000 ohms maximum) to the input of the TE-74 that needs calibration. (Record value as Rref_min.)
  2. Allow the input to settle (approximately 30 seconds), record the present value of the input resistance. (Record value as Rmin.)
  3. Connect a second reference resistance (40,000 ohms ± 100 ppm: 30,000 ohms minimum, 42,000 ohms maximum) to the input of the TE-74 that needs calibration. (Record value as Rref_max.)
  4. Allow the input to settle (approximately 30 seconds), record the present value of the input resistance. (Record value as Rmax.)
  5. Calculate the gain correction factor using equation below:
  6. Command the channel Field Gain to the calculated gain correction factor.
  7. Calculate the field Zero Reference value using the equation below:
  8. Command the channel Field Zero Reference to the calculated field Zero Reference.