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Programming the DC Source - 5
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To select GPIB bus triggers, use:
TRIG:ACQ:SOUR BUS
To select external triggers use:
TRIG:ACQ:SOUR EXT
Selecting the Sensing Function
Each output channel has its own measurement buffer. Since both voltage and current measurements are
supported, you must specify a measurement function before you generate a measurement trigger. Use the
following command to specify a measurement function:
SENS:FUNC "CURR", (@<channel list>) or
SENS:FUNC "VOLT", (@<channel list>)
Using this command makes it possible to measure output voltage on some channels while measuring
output current on other channels.
Output Settling Delay
If an output change has been programmed to occur in conjunction with a measurement trigger, the dc
source will delay the start of a measurement until the output has settled. This is an automatic function
that allows the output to settle to approximately 0.1% of final value for a representative load that is a
function of the selected sourcing mode. The representative load in voltage priority mode is a 20 ohm
resistor with the current limit set to MAXimum. The representative load in current priority mode is a zero
ohm short circuit.
To change the source settling delay, you must first change the source delay mode to MANual, then set a
value for the delay time. Use the following commands:
SOUR:DEL:MODE MAN, (@<channel list>)
SOUR:DEL:<time>, (@<channel list>) where <time> is specified in seconds.
The minimum time interval that can be programmed is specified by SENS:SWE:TINT. In addition to the
minimum time interval, the delay time required for a given measurement accuracy is also function of
load, measurement parameter, and required accuracy. It may be convenient to characterize the delay
required for a particular load so that the test throughput can be optimized. Use the MEAS:ARRAY query
to obtain a record of the voltage or current as a function of time after a source change, so that the best
speed/accuracy tradeoff can be made.
Generating Measurement Triggers
After you specify the appropriate trigger source, sensing function, and optional settling delay, generate
triggers as follows:
GPIB Triggers
Send one of the following commands over the GPIB:
TRIG:IMM (not affected by the trigger source setting)
*TRG
an IEEE-488 Group Execute Trigger bus command
EXTernal Triggers
Provide a negative-going TTL signal to the trigger input.