Rockwell Automation 1771-IXHR , D17716.5.80 HIGH RESOL.THERMOCOUPLE - Manual (Page 35)

Chapter
7Ć1
Module Calibration
In this chapter we tell you how to calibrate your module.
To calibrate your module you will need the following tools and equipment:
Tool or Equipment Description Model/Type Available from:
Precision Voltage Source 0-100mV, 1
µ
V resolution Analogic 3100, Data Precision 8200
or equivalent
Industrial Terminal and
Interconnect Cable
Programming terminal for A-B
family processors
Cat. No. 1770-T3 or Cat. No.
1784-T45, -T47, -T50, etc.
Allen-Bradley Company
Highland Heights, OH
The high resolution thermocouple/millivolt input module is shipped already
calibrated. If it becomes necessary to recalibrate the module, you must calibrate
the module in an I/O chassis. The module must communicate with the processor
and industrial terminal.
Before calibrating the module, you must enter ladder logic into the processor
memory, so that you can initiate BTWs to the module, and the processor can
read inputs from the module.
Calibration can be accomplished using either of two methods:
auto–calibration
manual
calibration
The auto–calibration method is recommended since it is easier and less time
consuming than manual calibration. Manual calibration can be used if you are
more familiar with this type of calibration, or if you desire to compensate for
thermocouple or lead error.
Auto–calibration calibrates the input by generating offset and gain correction
values and storing them in EEPROM. These values are read out of EEPROM
and placed in RAM memory at initialization of the module.
The auto–calibration routine operates as follows:
- Whenever a block transfer write (BTW) of length 28 is performed to the
module (any time after the module has been powered up), it interrogates
word 28 for a request for auto–calibration.
- The request can be for the following: offset calibration, gain calibration,
save operation (save to EEPROM).
When using auto–calibration, write transfer calibration words 20 through
27 must contain zeroes.
Chapter Objective
Tools and Equipment
Calibrating your Input
Module
About Auto-calibration