National Instruments PCI-6251 User Manual

7-36 | ni.com
Chapter 7 Counters
80 MHz Source Mode
In 80 MHz source mode, the device synchronizes signals on the rising edge of the source, and
counts on the following rising edge of the source, as shown in Figure 7-35.
Figure 7-35. 80 MHz Source Mode
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 7-36.
Figure 7-36. 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 7-37.
Figure 7-37. External Source Mode
Source
Synchronize Count
Source
Synchronize Count
Source
Delayed Source
Count
Synchronize

National Instruments PCI-6251 Specifications

General

Brand	National Instruments
Model	PCI-6251
Category	I/O Systems
Language	English