Rockwell Automation 1771-IR , D17716.5.76 RTD INPUT MODULE - Manual (Page 38)

Module Calibration
Chapter 7
7Ć5
Save Calibration Values
If any ”uncalibrated channel” bits (bits 10–15 of BTR word 9) are set, a save
cannot occur. Auto–calibration should be performed again, starting with offset
calibration. If the module has a faulty channel, the remaining functioning
channels can be calibrated by inhibiting calibration on the faulty channel.
The module can be run with the new calibration values, but will lose them on
power down. To save these values, proceed as follows:
1. Request a ”save to EEPROM” by setting bit 02 in BTW word 15 and
sending the BTW to the module. Refer to Table 7.A.
2. Queue BTRs to monitor for ”save complete”, ”EEPROM fault” and
”calibration fault.” An EEPROM fault indicates a nonoperative EEPROM;
a calibration fault indicates at least one channel was not properly offset or
gain calibrated and a save did not occur.
Note: During normal operation, make sure bits 00, 01 and 02 of BTW
word 15 are zero (0).
You calibrate each channel by applying a precision resistance across each
channel, comparing correct with actual results, and entering correction into the
corresponding calibration word for that channel. The correction takes affect
after it is transferred to the module by the corresponding BTW instruction in
your ladder diagram program. Always start with offset adjustment followed by
gain adjustment.
Before calibrating the module, you must enter ladder logic into processor
memory, so that you can initiate write block transfers to the module, and the
processor can read inputs from the module.
Words 9 through 14 in the write block transfer file are the module calibration
words. Word 9 corresponds to channel 1, word 10 to channel 2, and so on. Each
word is composed of two bytes: the upper byte is for offset correction and the
lower byte is for gain correction. Refer to Table 7.C.
Performing Manual Calibration