Technical data

Calibration Procedures 3
34980A Service Guide 67
34951A 4-Ch Isolated DAC Module
Each isolated DAC output channel can be measured and adjusted using the
internal DMM. The Internal DMM is recommended because it compensates
for ambient temperature.
The 34951A features “auto- calibration”. Upon receipt of the calibration
command, all channels on the DAC are adjusted using the internal DMM.
Additionally you may adjust ALL 34951A modules installed in the
instrument with one command. The adjustments require approximately 
one minute per module.
There are two ways to adjust the DACs, depending upon the state of
calibration security (see “Calibration Security" on page 47).
• If the instrument is secured for calibration when the adjustment is
begun, the adjustments are considered volatile. All adjustments are
discarded when power is cycled. This provides an easy means to make
immediate temperature- compensated adjustments to the DAC outputs
without overwriting stored calibration constants. 

When this type of adjustment is made, the calibration count 
(see page 48) is not advanced.
• If the instrument is unsecured for calibration, the adjustments are
written to non- volatile calibration memory. The calibration count 
(see page 48) is advanced.
NOTE
The 34951A 4-Ch Isolated DAC is intended to be adjusted frequently to
compensate for changes in the module’s environment (changes in
ambient temperature, changing the mainframe slot used, adding or
removing modules to a system). These adjustments can be made either
volatile or non-volatile as described below. The adjustment procedure is
given beginning on page 70.