Rockwell Automation 1746-XXXX SLC 500 4-Channel Analog I/O Modules User Manual - Manual (Page 103)

Publication 1746-UM005B-EN-P - June 2004
Optional Analog Input Software Calibration C-3
4. Using an analog input calibration source or your system’s input
device placed at the 20 mA position, capture the high value by
energizing the calibrate high input. Ensure that your high value
lies within the conversion range of your analog input.
5. Energize the calibrate input. This causes the SLC to calculate the
slope and offset values used to perform the error correction to
the analog input.
The analog channel is now calibrated to ± 3 LSB at the calibration
temperature. Use the offset error drift and gain error drift to calculate
the amount of additional error that can be introduced into your system
due to temperature variation.
The recommended calibration period is once every 6 months. If an
application has a wide range of operating temperatures, a software
calibration should be performed every 3 to 4 months.