Checking the System
For the Count when gate is high and the Count when gate is low modes, the TTL level of the gate enables or disables counting, depending on the mode that you set. If there is no input connected to the gate input, use the Count when the gate is in high mode.
For the modes Measure input high period, Measure input low period, and Measure total period, the data displays shown at the bottom portion of the dialog provide the status and the time between the most recent appropriate edges as shown in FIGURE 3.6, UDAS SYSCHECK Counter Test: Measure Input High Mode.
FIGURE 3.6 UDAS SYSCHECK Counter Test: Measure Input High Mode
The status field is looking for TTL transitions.
Select the Measure frequency radio button and the dialog shown in FIGURE 3.7, UDAS SYSCHECK Counter Test: Measure Frequency Mode opens.
