Rockwell Automation 1794-IF4I, -OF4I, IF2XOF2I, -IF4IXT, -IF4ICFXT, -OF4IXT, IF2XOF2IXT FLEX I/O Isolated Analog Modules - Manual (Page 130)

Publication 1794-6.5.8 - January 2010
128 Calibrating Your Module
Calibrating Current Outputs
Current calibration requires gain calibration followed by offset
calibration, and a limited gain calibration using corrected coefficients.
Gain Calibration for Current Outputs
1. Send a block transfer write to the module to set the output
values for gain voltage; F3CF hex for 20.0mA mode 8. Measure
the output. Calculate the gain correction for each channel as
follows:
gain_corr = (0.02A – measured_value) X 3202194.613
2. Enter these gain corrections in the output word for each channel
being calibrated. Record each of the values to be used later.
3. Send a block transfer write with the CK bit set to 1. With GO
high, the module will copy “gain_corr” coefficients (signed 2’s
complement format) from the data words into gain storage for
the selected channels. If RV is high, default values will be copied
to all channels.
4. Send a block transfer write with CK set to 0. With GO high, the
previously determined gain coefficients are stored into EEPROM
as directed by the channel selection.
5. Clear the IC bit to 0. Gain calibration is terminated.
Offset Calibration for Current Outputs
Refer to the output timing diagram when calibrating the module.
Normally all outputs are calibrated together. To calibrate the offset of
an output, proceed as follows:
1. If you are not calibrating all channels with the same
configuration, select the channel to be calibrated by setting the
bit for that channel.
2. Send a block transfer write (BTW) to the module with individual
channel bits set for the configuration desired for each output.
This effectively terminates any previous configuration of the
module/channel.