DNx-AI-208 Analog Input Layer
28
Tel: 508-921-4600
www.ueidaq.com
Vers:
4.6
Date: November 2013
File:
AI-208 App B.fm
© Copyright 2009
United Electronic Industries, Inc.
The Shunt Calibration method of calibration and reading uses a 4-wire sensor
configuration. When you use this method, you should permanently connect the
PS+ pin to the S+ pin and remove the jumper and other “6-wire” connections to
the PS+ pin. The only connection to PS+ should be the connection to S+ shown
in
bold
in
A low-level API function allows activation and precise measurement of Ra and
Rb.
Once Ra or Rb value is known, the value can be inserted into Equation 4 or 5 to
calculate the Gain Adjustment Factor.
B.4
Configuring
Framework
for Shunt
Calibration
Flow of operations
The shunt calibration will be performed using the following steps:
Measure bridge output voltage
without shunt.
Engage shunt and measure
bridge output voltage again.
Calculate what the bridge out-
put offset should be theoreti-
cally using Eq. 4 or 5.
Calculate Gain Adjustment Fac-
tor
Disengage shunt calibration
resistors and apply adjustment
factor to every measurement
from now on.
