62 Synchronizing Power Module Output Changes
The number of dwell points must equal the number of output points:
LIST:VOLT 3.0,3.25,3.5,3.75
LIST:DWEL 10,10,25,40
The only exception is for a dwell list with one value, which gives the same interval to all the points in the corresponding
voltage or current list.
Note Sending a VOLT [: LEV: IMM] or CURR [: LEV: IMM] command during an interval will override the list
output value for that interval. When the next interval begins, the output will be determined by the list
value for that interval.
Automatically Repeating a List
You can repeat a list by entering a LIST: COUNt parameter. The parameter determines how many times a list is executed or
sequenced. Enter an integer or enter the value INF to make the list repeat indefinitely. For example, to make the current list
2,3,12,15 repeat 5 times, send:
LIST:CURR 2,3,12,15
LIST:COUN 5
The LIST: COUNt parameter is stored by *SAV and restored by *RCL. The GPIB *RST value is 1.
Triggering a List
No list will execute without a trigger. How the list responds to a trigger depends on how you program the LIST: STEP AUTO
| ONCE command. The method you use will depend upon whether you want the list to be paced by dwell intervals or by
triggers.
Dwell-Paced Lists
For a closely controlled sequence of output levels, you can use a dwell-paced list. Each list output point remains in effect
for the dwell time associated with that point. When the dwell time expires, the output immediately changes to the next point
in the list.
For dwell pacing, program LIST: STEP to AUTO (see Figure 5-3-A). The dwell-paced list requires only a single trigger to
start the list. The trigger subsystem remains in the dwelling state until the list is completed. If LIST: COUN is greater than 1,
the entire list is repeated until the count has been satisfied (see Figure 5-1-B).
Trigger-Paced Lists
If you need the output to closely follow asynchronous events, then a trigger-paced list is more appropriate. Program LIST:
STEP to ONCE (see Figure 5-3-B). Now expiration of a dwell interval returns the trigger subsystem to the Initiated state.
The subsystem then waits for a trigger to start the next dwell interval. During this time, the power module output remains at
the level set by the last executed point in the list.
Note If the subsystem is not in the dwelling state, a TRIGger [: IMMediate] command will sequence the next point
in the list.