Rockwell Automation 1771-N SERIES High Resolution Analog Module User Manual - Manual (Page 69)

Chapter
6
Publication 1771ĆUM127B-EN-P - December 2002
Module Calibration
In this chapter we tell you how to calibrate your module. Your
module is shipped from the factory already calibrated. This
chapter tells you how to recalibrate or change calibration.
In order to calibrate your analog module you will need the following
tools and equipment:
Tool or Equipment Description
Precision Voltage Source 0-10V, 1µV resolution
High Precision Resistors:
649 ohm, 0.01%, 5ppm/ o C
1 ohm, 0.1%, 5ppm/ o C
Lower Precision Resistors:
If calibration to rated accuracy is not required, lower precision resistors
can be used. Add percentage of tolerance and temperature coefficient
error for expected accuracy. Refer to 6.A and 6.B below.
Precision Resistors
OR
Accuracy: Minimum three decades;
Decade one - 10 ohm decade, 1 ohm per step, better than 0.005 ohms (0.5% accuracy)
Decade two - 100 ohm decade, 10 ohm per step, better than 0.005 ohms (0.05% accuracy)
Decade three - 1000 ohm decade, 100 ohm per step, better than 0.01% accuracy
Precision Decade
Resistor Box
Any vendor's model that meets or exceeds the above specifications can be used. The user is
responsible for assuringthat the decade box maintains accuracy by periodic calibration as specified by
the vendor. As a service to its customers, AllenĆBradley offers this partial list of vendors who can supply
decade resistor boxes that meet or exceed the specifications.
Electro Scientific Industries
Portland, OR
Series DB 42
IET Labs
Westbury, NY
HARS-X Series
Julie Research Labs
New York, NY
DR 100 Series
Precision Multimeter
50mA, 1µA resolution
10V, 1µV resolution
Industrial Terminal and
Interconnect Cable
Programming terminal for A-B family processors
If calibration to rated accuracy is not required, lower precision
resistors can be used. Add the percentage of tolerance and the
temperature coefficient error for expected accuracy.
Resistor Accuracy
Resistors change value over time. Both load life and temperature
reduce the accuracy. The best way to determine the resistance of a
resistor is to measure its value to the accuracy needed under the
conditions in which it is used.
Chapter Objective
Tools and Equipment