National Instruments NI 6232 - Manual (Page 113)

Chapter 7 Counters
NI 6232/6233 User Manual 7-40 ni.com
Other Internal Source Mode
In other internal source mode, the device synchronizes signals on the
falling edge of the source, and counts on the following rising edge of the
source, as shown in Figure 7-35.
Figure 7-35. Other Internal Source Mode
External Source Mode
In external source mode, the device generates a delayed Source signal by
delaying the Source signal by several nanoseconds. The device
synchronizes signals on the rising edge of the delayed Source signal, and
counts on the following rising edge of the source, as shown in Figure 7-36.
Figure 7-36. External Source Mode
Source
Synchronize Count
Source
Delayed Source
Synchronize
Count