Rockwell Automation 1746-INT4 Thermocouple/MV Isolated/ User Manual - Manual (Page 105)

Publication 1746-UM614B-EN-P - September 2007
Channel Calibration 105
Calibration Procedure
To perform this calibration procedure, you need a precision dc
voltmeter and precision power supply that displays and maintains a
calibration voltage to 1/1000 of a millivolt: at 0.000 mV and
90.000 mV.
Prepare for calibration by removing the thermocouple leads from the
input terminals of the channels that you want to calibrate. Switch the
SLC processor to Run mode so it can execute the calibration ladder
logic. For convenience, we suggest that you calibrate all four channels
at the same time.
1. With your programming terminal, enter calibration code 1001
Hex into the data table address for configuration word 5.
2. Observe status words 0…3, 6 and 7.
The module returns the code CAL4 Hex in status words 6 and 7.
It also clears channel data words 0…3.
3. Short circuit the pairs of input terminals for the channels you
want to calibrate.
Make the jumper as short as possible.
4. With your programming terminal, enter calibration code 1002
Hex into the data table address for configuration word 5.
5. Observe bits 0…3 in status word 4.
If all the channels you are calibrating see zero voltage, the
module returns status-OK bits set, one bit for each channel (F
Hex for all four channels). Otherwise, the module returns
channel status bits set to zero.
6. Apply 90.000 mV to the pairs of input terminals, all in parallel,
for the channels you are calibrating.
Make your leads as short as possible.
7. With your programming terminal, enter calibration code 1004
Hex into the data table address for configuration word 5.