Calibration - HP E1419A User Manual

Chapter 6
The Calibration subsystem provides for two major categories of calibration.
1. "A/D Calibration"; In these procedures, an external multimeter is used to
calibrate the A/D gain on all 5 of its ranges. The multimeter also determines the
value of the HP E1419's internal calibration resistor. The values generated from
this calibration are then stored in nonvolatile memory and become the basis for
"Working Calibrations. These procedures each require a sequence of several
commands from the CALibration subsystem (CAL:CONFIG...,
CAL:VALUE..., and CAL:STORE ADC). Always execute *CAL? or a
CAL:TARE operation after A/D Calibration.
2. "Working Calibration", of which there are three levels (see Figure 6-3):
"A/D Zero"; This function quickly compensates for any short term A/D
–
converter offset drift. This would be called the auto-zero function in a
conventional voltmeter. In the HP E1419 where channel scanning speed is of
primary importance, this function is performed only when the CAL:ZERO?
command is executed. Execute CAL:ZERO? as often as your control setup
will allow.
"Channel Calibration"; This function corrects for offset and gain errors for
–
each module channel. The internal current sources are also calibrated. 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 CAL:SETup command.
"Channel Tare"; This function (CAL: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 (CAL: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. CAL:TARE automatically executes a *CAL?.

CALibration

HP E1419 Command Reference 211