CALibration
The
CALibration
subsystem provides for two major categories of calibration.
1. “ A/D Calibration” : In these procedures, an external multimeter is used to
determine the actual voltage or resistance values of the HP E1313/E1413’s
internal calibration sources. The known values are then sent to the
HP E1313/E1413 where they are stored and used to perform internal A/D
calibration. These procedures each require a sequence of several commands
from the
CALibration subsystem (CALibration:CONFigure:
…
,
CALibration:VALUE:
…
, and
CALibration:STORe ADC
). For an actual
calibration example see the HP E1313A/E1413C Service Manual. Always
execute
*CAL?
or a
CALibration:TARE
operation after A/D Calibration.
2. “ Working Calibration” , of which there are three levels (see Figure 5-2):
–
A/D Zero
This function quickly compensates for any short term A/D converter offset
drift. This would be called the autozero function in a conventional voltmeter.
In the HP E1313/E1413, where channel scanning speed is of primary
importance, this function is performed only when the
CALibration:ZERO?
command is executed.
–
Channel Calibration
This function corrects for offset and gain errors for each module channel. The
internal current sources are also measured. This calibration function corrects
for thermal offsets and component drift for each channel out to the input side
of the Signal Conditioning Plug-On (SCP). All calibration sources are
on-board and this function is invoked using either the
*CAL?
or
CALibration:SETup
command.
–
Channel Tare
This function (
CALibration:TARE
) corrects for voltage offsets in external
system wiring. Here, the user places a short across transducer wiring and the
voltage that the module measures is now considered the new “ zero” value for
that channel. The new offset value can be stored in non-volatile calibration
memory (
CALibration:STORe TARE
) but is in effect whether stored or not.
System offset constants which are considered long-term should be stored.
Offset constants which are measured relatively often would not require
non-volatile storage.
CALibration:TARE
automatically executes a
*CAL?
.
CALibration
Chapter 5
HP E1313/E1413 Command Reference 175
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