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Lake Shore Model 331 Temperature Controller User’s Manual
8.9.2.4
Resistive Input Ranges Calibration
Purpose
To determine the input offset and gain errors when the input is configured for the resistive ranges
and provide offset and gain calibration constants back to the Model 331. This step will calibrate all
resistive ranges with reversing both on and off.
Process
1. Configure the input for the resistive range to be calibrated.
2. Reset the calibration constants to their default values using the
CALRSTZ
and
CALRSTG
commands.
EXAMPLE:
Input: A
Range: 100
Ω
Plat/250, Reversal Off
Zero Offset Reset Command:
CALRSTZ A,2
Gain Reset Command:
CALRSTG A,2
3. Short all four terminals, (I+, I–, V+, V–), of the input together, do not tie the terminals to ground.
4. Via the interface obtain the input reading using the
CALREAD?
command and record this
number.
5. Program the offset calibration by negating the value read in the previous step and providing it
using the
CALZ
command.
EXAMPLE:
Input: A
Range: 100
Ω
Plat/250, Reversal Off
CALREAD?
Reading: +000.003
Calibration Command:
CALZ A,2,-0.003
6. From Table 8-2 select the calibration resistor for the range being calibrated and use the DMM
in 4-lead resistance measurement mode to measure the value of the resistor to the tolerance
shown.
7. Attach the calibration resistor to the Model 331 sensor input. Be sure to connect the resistor
using proper 4-lead connection techniques.
8. Via the interface obtain the input reading using the
CALREAD?
command and record this
number.
9. Program the gain calibration by dividing the actual resistance of the calibration resistor by the
value read in the previous step and provide the result using the
CALG
command. Note that the
gain calibration constant will always be within 5% of 1.00000.
EXAMPLE:
Input: A
Range: 100
Ω
Plat/250, Reversal Off
Measured Value of Calibration Resistor: 100.0250
Ω
CALREAD?
Reading: 100.145
Constant Calculation: 100.0250 / 100.145 = 0.99880
Calibration Command:
CALG A,2,0.99880
10. Send the
CALSAVE
command to save the constants in the E
2
prom.
11. Repeat the resistive input ranges calibration for all resistive ranges with reversal on and off.
12. Repeat all of Paragraph 8.9.2 for second input if Diode/Resistor.
Service
8-13