Running Autocal; When To Use Autocal - Agilent Technologies 3458A User Manual

Note

Running Autocal

When to Use Autocal

routine are:
•
The DCV routine enhances all measurement functions. This routine takes
about
1 minute to perform.
•
The AC routine performs specific enhancements for AC or AC+DC voltage
(all measurement methods), AC or AC+DC current, direct- or sub-sampled
digitizing (AC- or DC-coupled), frequency, and period measurements. The
AC routine takes about 1 minute to perform.
•
The OHMS routine performs specific enhancements for 2 or 4-wire ohms.
DC current, and AC current measurements. The OHMS routine takes about
10 minutes to perform.
•
The ALL routine enhances all measurement functions by performing all of
the above routines. The ALL routine takes about 11 minutes to perform.
You should not cycle power or reset the multimeter while an autocal routine
is being performed. If you do, the multimeter generates the ACAL
REQUIRED error (since many or all of its autocal constants have been
erased). You must then perform the ALL routine to eliminate the error.
Since the DCV routine applies to all measurement functions, you should
perform the DCV autocal before performing the AC or OHMS autocal, or
perform ALL of the routines (see second example below).
Suppose you intend to make 4-wire ohms measurements. The DCV autocal
routine increases the short term accuracy for all measurements and the
OHMS autocal enhances resistance measurements (and current
measurements). The following program performs the DCV autocal followed
by the OHMS autocal.
10 OUTPUT 722; "ACAL DCV"
20 OUTPUT 722; "ACAL OHMS"
30 END
If autocal is secured (it is not secured when shipped from the factory), you
must enter the security code to perform autocal; refer to the ACAL command
in Chapter 6 for more information. You can perform all of the autocal
routines (DCV first, followed by OHMS and AC) by sending:
OUTPUT 722; "ACAL ALL"
Always disconnect any input signals before performing autocal. If you leave
an input signal connected to the multimeter, it may adversely affect the
autocal and subsequent measurements.
For maximum accuracy, we recommend performing ACAL ALL once every
24 hours or when the multimeter's temperature changes by ± 1
it was last externally calibrated or from the last autocal. (We recommend that
the calibrator store the multimeter's internal calibration temperature using
Chapter 3 Configuring for Measurements
°
C from when
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