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For the 2561 HTPRT module the list of parameters includes 0_ADJ and
10_ADJ as described above. The list also includes the calibration date (CAL
DATE) parameter, used to record the date the module was calibrated, and the
SER NUM parameter, used to record the serial number of the module.
8.4.3
Calibration Procedure
Calibration requires adjustment of the 0_ADJ, and 10_ADJ parameters at two
specific input resistances. If the resistances used are approximately 0Ω and
10Ω respectively the adjustments are independent and the procedure is simple.
Either channel can be used for calibration. Set the conversion type to R(Ω) to
display resistance (see Section 5.2.1.1 ). The accuracy required of the resis-
tance standards is 1/4 of the instrument accuracy: that is ±0.000025Ω at 0Ω and
±0.00012Ω (12 ppm) at 10Ω. The recommended procedure is as follows:
1.
Connect a 0Ω resistor to the input and measure its resistance. If a short-
ing wire is used, the wire should run from the inside black terminal to
the inside red terminal to the outside red terminal then back across to the
outside black terminal. Note the average error in the measurement. Ad-
just the 0_ADJ parameter by subtracting the measured error. For exam-
ple, if the input is exactly 0.0Ω and readout shows –0.211mΩ, 0_ADJ
should be adjusted by adding 0.000211 to it.
2. Connect a 10Ω resistor (12 ppm accuracy) to the input and measure its
resistance. Note the average error in the measurement. Adjust the
10_ADJ parameter by subtracting the measured error. For example, if the
input is exactly 10.0Ω and the readout shows 10.02955Ω, 10_ADJ
should be adjusted by subtracting 0.02955 from it.
3.
Record the date with the calibration date parameter.
4.
Verify the accuracy at 0Ω, 1Ω or 25Ω, 10Ω, and 25Ω. Verify the accu-
racy of both channels with selected resistances. The accuracy must be
within the short-term accuracy given in the specifications.
CALIBRATE DEVICE: HPRT
0 ADJ: 0.0
10 ADJ: 0.0
CAL DATE: 05-21-96
SER NUM: A38123
8 2561 HTPRT Module
Calibration
123
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