National Instruments NI 6602 User Manual page 14

© National Instruments Corporation
This feature is useful in applications with two or more counters that are
armed by an external start trigger, or that use the same PFI line as a counter
control signal. Pad synchronization is only useful if the counters involved
are using one of the internal timebases. A counter is using maximum
timebase as its source if the synchronous counting mode is enabled for
that counter.
Figures 2-2 and 2-3 illustrate how pad synchronization can be useful.
These figures assume a 0.5 and a 0.75 SOURCE cycle delay between the
PFI 38 input pin, and CTR 0 GATE and CTR 1 GATE, respectively.
Figure 2-2 shows counter 0 at the gate edge on PFI 38 one source period
before counter 1. Figure 2-3 shows both counters at the gate edge on PFI 38
at the same time.
Counter
Source
PFI 38
at Input To ASIC
PFI 38
at CTR 0 GATE
PFI 38
at CTR 1 GATE
Sampled
GATE at Ctr0
Sampled
GATE at Ctr1
Figure 2-2. Counter 0 at Gate Edge on PFI 38 One Source Period before Counter 1
1/2 Cycles
1/4 Cycle
2-3
Chapter 2 Device Overview
NI 660x User Manual