SCXI-1125Calibration Procedure 8 ni.com
•filterMode—1
•cutoffFrequency—10,000
9. Connectthe calibratorto the analog input you want to adjust. Refer
to Figure 1 to determine the pins on the 96-pin front connector that
correspondto the positive and negative inputs of the specified channel.
Forexample, the positive input for channel 0 is pin A32, which is
labeled CH0+. The negativeinput for channel 0 is pin C32, which
is labeled CH0–. If you are using an SCXI-1320 terminal block
connected to the SCXI-1125, connect the calibrator to the CH0+
and CH0–inputs.
10. Connect the DMM to the positive output on pin 3 (MCH0+) and
negativeoutput on pin 4 (MCH0–) on the rear panel connector.
Figure 2 showsthe 50-pin rear panel connect or.
Tip Foreasy access to individual pins, use a screw terminal adapter connected to a
50-pin terminal block.
11. Set the calibrator voltage to the positive test point value in Table1.
12. Read the voltage from the DMM. Record the actual DMM reading,
whichis output1, and the calibrator output voltage, which is volt1,for
later use.
13. Set the calibrator to the negativetest point value for the same gain.
Skip anyinput lim its that ares pecifiedas 0.0 V. Youneed only upper
and lowerlimits for adjustment.
14. Read the voltage from the DMM. Record the actual DMM reading,
output2, and the calibrator output voltage, voltage2.
Younow have two pairs of data points, (volt1,output1) and (volt2,
output2), where volt is the calibrator reading and output is the DMM
reading.
15. Convertth eDMM voltage readings (outpu t1 andou tput2)tobinary
readings (binary1 and binary2) by using one of the following
equations:
Forexample, using a 12-bit product such as a PCI-MIO-16E-1 and
obtaining a DMM reading of –9.9 V,you would have the following
results:
binary reading =(–9.9/20)× 212 =–2027.52
binary reading for 12-bit E Series products (binary) output
20
-----------------
212
×=
binary reading for 16-bit E Series products (binary) output
20
-----------------
216
×=