Allen-Bradley 1794-IRT8 - Tools, Setups, and Wiring for Calibration; Manual Calibration Procedures (Offset, Gain)

Publication 1794-6.5.12 - November 1997
6-2 Calibrating Your Module
Tools and Equipment To calibrate your Thermocouple/RTD/mV input module, you will need
the following tools and equipment:
Manually Calibrating your
RTD/Thermocouple/mV
Input Module
You must calibrate the module in a FLEX I/O system. The module must
communicate with the processor and an industrial terminal. You can
calibrate input channels in any order, or all at once.
Before calibrating your module, you must enter ladder logic into the
processor memory, so that you can initiate block transfer writes (BTW) to
the module, and read inputs from the module (BTR).
Important: To allow the internal module temperature to stabilize, apply
power to the module for at least 20 minutes before
calibrating.
To manually calibrate the module:
1. Apply a reference to the desired input(s).
2. Send a message to the module indicating which inputs to read and
what calibration step is being performed (offset).
3. The module will return a BTR which echoes back the message sent in
the BTW word.
The module stores this input data.
4. Apply a second reference signal to the module.
5. Send a second message indicating which inputs to read and what cali-
bration step is being performed (gain).
6. The module computes new calibration values for the inputs and
returns a BTR which echoes back the message sent in the BTW word.
If the calibration is cannot be completed, the module returns a fault
message.
Tool or Equipment Description
Precision Resistors
High Precision Resistors:
383Ω, 0.01%, 5ppm/°C
100Ω, 0.01%, 5ppm/°C
10 Kohm, 0.5%, 5ppm/°C
Precision Voltage Source ±320mV, 1µV resolution Analogic 3100, Data Precision 8200 or equivalent
Industrial Terminal and
Interconnect Cable
Programming terminal for A-B family processors
Allen-Bradley PLCs