2635A
Users Manual
2-32
Typical
Required
TRIg
ENTER
Selecting a Trigger Option. Press the SHIFT
key and then the MON key to access the trigger
option menu. Press the up/down arrow keys to
select either ALAr (Alarm) (Monitor-Alarm trigger),
On (On) (External trigger), or OFF (Off) (no
trigger option selected), then press the ENTER
key.
ALAr
On
OFF
SHIFT
MON
op31f.eps
Figure 2-19. Scan Triggering Options
Totalizer Operation
Perform the procedure in Figure 2-20 to use the totalizer feature. The totalizer count can
be monitored when the instrument is active or inactive. The totalizer is an internal
counter that sums contact closures or voltage transitions. Connection is at the rear panel
DIGITAL I/O connector, pins SUM and GROUND. A contact closure between SUM and
GROUND or a voltage transition applied to SUM (referenced to GROUND), will cause
the totalizer to advance by one count. The maximum count allowed is 65535 and the
maximum count rate is 5 kHz. Voltages trigger on a low-to-high transition at a nominal
threshold of +1.4 volts. A contact debounce feature is available when the instrument is
operated through a computer interface. (See Chapter 4, "Computer Operations.")