Keithley 2000, User Manual, Page: 82 / 280

NOTE
If the reading count divided by the scan list length is not an integer, it is rounded up.
For example, if the reading count is 15 and the scan list length is 10, there will be two
output triggers for scanning.
The differences between stepping and scanning counters for bus commands are summarized
in Table 3-3.
Timing
Another configuration option for stepping and scanning is the timing of channel closures. The
example of Figure 3-15 shows how different settings of TIMER and DELAY affect these oper-
ations. These are the Timer control source and the Delay block shown in the trigger models of
Figures 3-12 and 3-13.
• With the timer ON and set to five seconds and delay set to AUTO, channels are stepped
through at five-second intervals with an output trigger after each closure. A scan opera-
tion yields ten channels scanned immediately with an output trigger at the end of the
scan.
• With the timer OFF and the delay set to MANual for five seconds, stepping and scanning
through the channels is timed the same. The difference is in the number of output trig-
gers, with stepping sending a trigger after each channel closure and scanning sending a
trigger at the end of the scan.
When using both the timer and delay parameters, the timer is not started until after the delay.
For example, if the timer is two minutes and the delay is ten seconds, the timer is not started until
10sec after pressing SCAN. Each successive scan will occur at 2:10.0, 4:10.0, etc.
If the total delay time per scan is greater than or equal to the timer setting, the timer condition
is already satisfied and, effectively, is ignored.
Table 3-3
Bus commands parameters for stepping and scanning counters
Operation :SAMPle:COUNt :TRIGger:COUNt
STEP 1 reading count
SCAN scan list length (reading count) / (scan list length)
3-28 Measurement Options