80 Mhz Source Mode; External Or Internal Source Less Than 20 Mhz - National Instruments cDAQ-9138 User Manual

Chapter 5 Counters

80 MHz Source Mode

In 80 MHz source mode, the controller synchronizes signals on the rising edge of the source, and
counts on the third rising edge of the source. Edges are pipelined so no counts are lost, as shown
in Figure 5-38.
Figure 5-38. 80 MHz Source Mode
80 MHz Source
Synchronize Count

External or Internal Source Less than 20 MHz

With an external or internal source less than 20 MHz, the module generates a delayed Source
signal by delaying the Source signal by several nanoseconds. The controller 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 5-39.
Figure 5-39. External or Internal Source Less than 20 MHz
Source
Synchronize
Delayed Source
Count
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