Keithley 194 Instruction Manual page 51

5. Change the sampling interval to 5msec as follows. Press
RATE, FREQiTIME (if necessary to display time units),
5, ms. The sampling interval has now been changed to
5msec.
6.
Press DELAY to program delay period. If necessary, use
the FREQiTIME key to display the number of samples.
Note that the number samples to delay has been
changed from 50 to 10 because of the change in sampl-
ing interval from lmsec to 5msec.
Discussion
The trigger delay parameter tells the instrument where to
begin storing readings relative to the trigger point. If the
parameter is zero, no delay occurs, and the trigger point
is assumed to be the same as the first buffer sample.
However, if the delay parameter is non-zero, the first sam-
ple location will be moved in accordance with the pro-
grammed delay parameter.
Figure 3-l will help to demonstrate the basic concept
behind delayed triggering. In Figure 3:1(A), the delay is
zero, so the measurement begins at the trigger point. In
(B), which shows a positive delay, the measurement se-
quence begins some time after the trigger occurs. That time
period is, of course, determined by the programmed delay
value.
In Figure 3-l(C), a negative delay is shown, with the first
measurement occuring ahead of the trigger stimulus. The
amount of delay is again determined by the programmed
delay parameter.
Figure 3-1. Trigger Delay
3-12