Fluke NetDAQ 2640A, Service Manual

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Performance Testing and Calibration
Calibration
4
4-25
8. Verify Totalizer Count The Spy window summarizes the Totalizer count. Note the
Totalizer is incrementing at 1-second intervals as it counts the Trigger Output pulse
at the start of each scan.
9. Close Spy Window To close the Spy window, double-click the upper left-hand
corner control-menu box.
10. Stop Scanning Click the Stop Instrument button on the Button Bar to stop
instrument scanning.
Calibration 4-30.
The instrument features calibration that is completed over the NetDAQ networked data
acquisition unit RS-232 interface, and it is not necessary to open the instrument case.
Using known reference sources, closed-case calibration has many advantages. There are
no parts to disassemble, no mechanical adjustments to make, and the instrument can be
calibrated by an automated instrumentation system. The instrument should normally be
calibrated on a regular cycle, typically every 90 days to 1 year. The chosen calibration
cycle depends on the accuracy specification you wish to maintain. The instrument should
also be calibrated if it fails the performance test or has undergone repair.
The calibration procedure uses the CAL ENABLE switch under the Calibration Seal on
the instrument front panel. Do not press CAL ENABLE unless you intend to calibrate
the instrument. If you have entered calibration and wish to exit, press CAL ENABLE
until CAL is removed from the primary display, or just turn the instrument power off.
Once the instrument is in calibration mode, closed-case calibration is made for the four
calibration groups as follows:
•
Volts DC
•
Volts AC
•
Resistance
•
Frequency
Once begun, each group must be completed successfully for the results of the calibration
to be made permanent. It is not necessary to perform all calibration groups.
Methods of Calibration 4-31.
There three methods of instrument calibration as follows:
•
Automatic using Fluke MET/CAL software MET/CAL is a software package
developed by Fluke that automates the calibration of Fluke instruments and popular
instruments from other selected manufacturers.
•
Semiautomatic using NetDAQ Logger for Windows Calibration takes place in
conjunction with NetDAQ Logger for Windows, that is, a feature of the software is
used to calibrate the instrument. Since calibration is accomplished over an RS-232
connection between the instrument RS-232 port and a host computer serial COM
port, it is not necessary to have a network connection to accomplish calibration.
•
Manual using a terminal and individual commands Calibration takes place using
a host computer in a terminal mode. With this method all commands and responses
are considered individually.