Fluke 2640A Service Manual page 162

NetDAQ
Service Manual
4. Resolve any calibration problems based on the following:
CAL 3
CAL_REF?
CAL_STEP?
CAL_REF?
CAL_STEP?
CAL_REF?
CAL_STEP?
CAL_REF?
CAL_STEP?
CAL_REF?
CAL_STEP?
4-40
The 5700A provides a limited set of reference resistors where the best resistor for
each range is at 63.3% of full scale. This will give very good results, but making the
measurement closer to the full scale value using fixed resistors may give better
results. When you are using fixed resistors, you must use the CAL_REF command to
tell instrument the value of the new reference resistor. When you are using fixed
resistors, you connect the leads as they are for any four-wire ohms measurement.
•
An execution error !> is returned by the CAL_STEP? command if the full scale
measurement is off by more than 5% from the target or if the zero measurement
is off by more than 1% of full scale. When an error is detected, the cal constant
is not updated, and the procedure remains at the same step.
•
When CAL_STEP? reports an execution error !> due to an out-of-range
measurement, it returns the raw measured reading to give you an indication of
what was measured. When CAL_STEP? completes successfully, it returns the
reference value.
•
If CAL_STEP? returns an execution error !> while measuring the four-wire
short on channels 2 and 12, the procedure freezes at the internal step that
measures the short. This way, you can send a CAL_REF? command and it will
return 0 W, indicating that the problem was probably caused by a misapplied
short on channels 2 and 12.
•
A device-dependent error is returned by the CAL_STEP? command if an internal
error such as a measurement timeout is detected. When an error is detected, the
cal constant is not updated, and the procedure remains at the same step.
•
An execution error !> is returned by the CAL_REF command if the specified
reference is less than 33% of full scale or greater than 100% of full scale for any
range.
Table 4-7. Manual Resistance Calibration
Command Response
=>
+190.000E+0
+190.000E+0
+1.90000E+3
+1.90000E+3
+19.0000E+3
+19.0000E+3
+190.000E+3
+190.000E+3
+1.90000E+6
+1.90000E+6
Action
Puts NetDAQ in resistance calibration.
5700A - Source 190 ohms
NetDAQ computes the calibration constant and returns
the calibrated reading. Allow several seconds.
5700A - Source 1.9k ohms
NetDAQ computes the calibration constant and returns
the calibrated reading. Allow several seconds.
5700A - Source 19k ohms
NetDAQ computes the calibration constant and returns
the calibrated reading. Allow several seconds.
5700A - Source 190k ohms
NetDAQ computes the calibration constant and returns
the calibrated reading. Allow several seconds.
5700A - Source 1.9M ohms
NetDAQ computes the calibration constant and returns
the calibrated reading. Allow several seconds.