User manual

Table Of Contents
3152B User Manual Publication No. 980935 Rev. M
3-12 Operation Astronics Test Systems
internal trigger generator must be larger
than the period of the waveform.
trig:sour ttlt<n,1> This selects and activates
one or more of
the VXIbus backplane triggers (TTLTrg0
through TTLTrg7)
as the active source for
trigger events.
If more than one input is
activated, the instrument will accept trigger
events from all active trigger lines.
Note
that if one of the lines is
designated as an
output, it cannot be used as an active
source at the same time.
trig:sour bus This selects the software
trigger as the
active source for trigger events.
Selecting the
Trigger Level
The Trigger Level command sets the threshold level for
the trigger
input connector only. The trigger level is adjustable from -10
V to
+10 V using the following command:
Trig:lev <value> This
programs the trigger level threshold
for signals that are applied to the front-
panel TRIG IN connector.
The default value is 1.6 V which is appropriate for TTL signals.
Selecting the
Trigger Slope
The Trigger Slope command selects between positive-
and
negative-edge triggering.
The inputs that will be affected by this
command are: Front-panel TRIG IN connector, TTLTr
g lines 0
through 7, and ECLTrg line 0.
Transitions must cross the trigger
level threshold to trigger a response. Use the following commands
to select slope sensitivity for trigger events:
trig:slop pos TTLTrg lines: This
sets the 3152B to
respond to negative-going transitions only
(direction is reversed for TTLTrg lines).
All other inputs: This
sets the 3152B to
respond to positive-going transitions only.
trig:slop neg TTLTrg lines: This
sets the 3152B to
respond to positive-
going transitions only
(direction is reversed for TTLTrg lines).
All other inputs: This
sets the 3152B to
respond to negative-going transitions only.