Teledyne LeCroy PXA125 User Manual
Page 194
User Manual PXA125
Programming Reference 4-76
SEQuence:ADVance{AUTOmatic|STEP|SINGle|MIXed}
Purpose
This command will select the sequence advance mode. The way the instrument advances through the
sequence links can be specified by the user.
•
AUTOmatic - specifies continuous advance where the generator steps continuously to the end of the
sequence table and repeats the sequence from the start. For example, if a sequence is made of three
segments 1, 2 and 3, the sequence will generate an infinite number of 1,2,3,1,2,3,1,2,3…waveforms. Of
course, each link (segment) can be programmed with its associated loop (repeat) number. AUTO is the
default sequence advance mode.
•
In
STEP advance mode, the sequence is advanced to the next waveform only when a valid trigger is
received. The output of the PXA125 generates the first segment continuously until a trigger signal
advances the sequence to the next segment. If repeats were selected for a segment, the loop counter is
executed automatically.
•
In
SINGle advance mode, the generator idles between steps until a valid trigger signal is sensed. This
mode operates with trigger mode only. An attempt to select the SING advance mode when the PXA125
is in continuous operating mode will generate an error. After trigger, the generator outputs one
waveform cycle. Then, the output level idles at a DC level equal to the last point of the last generated
waveform. If loops (repeats) were programmed, the output will repeat this segment every time a trigger
is received. Only after executing all of the programmed loops will the sequence step to the next
assigned segment.
•
MIXed mode is a special mode, which combines continuous step advance with single step advance in a
sequence. There are three conditions for the sequence generator to operate in this mode:
1) The PXA125 must be set to operate in continuous mode
2) Select the MIX sequence advance mode
3) Assign the mixed mode bits for each sequence step in your SEQ:DEF command. “0” programs normal
advance, “1” programs trigger advance. Step with a “0” bit assigned to it will advance automatically to
the next step. If “1” is assigned to a step, the instrument will generate this step and its associated
number of repeats continuously and only a valid trigger signal will advance this step to the next step.
SEQuence:ADVance?
Response and default
The PXA125 will return the AUTO, STEP, SING, or MIX depending on the present sequence advance mode
setting. Default value is AUTO
SEQuence:ADVance:SOURce{EXTernal|INTernal|TTLTrig
Purpose
This command will select the sequence advance source. The source of the event causing sequence advance
can be specified by the user. The backplane on the PXI chassis has some signals on the P2 connector that
allow inter-instrument communication and synchronization. Among these lines, there are some trigger lines,
STAR trigger, and local bus lines. There are 8 trigger lines that can serve as source or target. Normally, these
lines are designated as tri-state lines. The TRIG:SOUR:TTLT
input.
•
•
•