Monitoring For Cal Violations; Monitoring Calibration Constants - Agilent Technologies 3458A Calibration Manual

Monitoring For CAL
Violations

Monitoring Calibration Constants

10 Chapter 1 3458A Calibration Introduction
CAL. (or ACAL if secured) is executed. If autocal is secured, the calibration
number is also incremented by 1 whenever an autocal is performed; if
unsecured, autocal does not affect the calibration number.
Note
The multimeter was adjusted before it left the factory. This has incremented
the calibration number. When you receive the multimeter, read the
calibration number to determine the initial value you start with. The
procedure for reading the number of calibrations is presented after this
note.
Read the number of calibrations with the following procedure:
1. Access the CALNUM? command. In the full command menu, press
the blue SHIFT key then the C menu key. Use the
display the CALNUM? command. (Full command menu is obtained
by pressing the blue SHIFT key, the "menu" key, the
ENTER key.)
2. Press the ENTER key.
3. The display indicates CALNUM and the current number of
calibrations.
You can use the CALSTR command in conjunction with the CALNUM?
command to monitor for calibration (CAL) violations. After each authorized
calibration has taken place, use the CALNUM? command to access the
current number of calibrations as described in the previous section. Store this
number in the calibration string (must be done remotely) with the CALSTR
command i.e. OUTPUT 722;"CALSTR 'calnum = 270' ". At any later time,
you can execute the CALNUM? and CALSTR? commands and compare the
two calibration numbers. If the CALNUM is greater than the CALSTR entry,
calibration security has been violated and unauthorized adjustments
performed.
The following example illustrates monitoring for CAL violations:
1. After adjustments are performed, execute CALNUM?. Display shows
"CALNUM 270"
2. Remotely execute OUTPUT 722;"CALSTR 'CALNUM=270' "
3. At a later time you can verify if CAL has been violated by executing
CALNUM? and CALSTR shift ? to see if CALNUM is greater than
that stored in CALSTR.
Each time you do an ACAL, most calibration constants are recalculated.
Executing an ACAL ALL recalculates 197 of the 253 calibration constants.
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