National Instruments DAQ X Series User Manual page 149

The behavior for each transition can be thought of as a state machine. If a
line transitions and stays high for two consecutive filter clock edges, then
one of two options occurs:
•
•
© National Instruments
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Case 1—If no transitions have occurred on the other lines, the
transition propagates on the second filtered clock edge, as shown in
Figure 6-13.
Stable
Digital Input P0.A
Digital Input P0.B
Filter Clock
Filtered Input A
Filtered Input B
Figure 6-13. Case 1
Case 2—If an additional line on the bus also has a transition during the
filter clock period, the change is not propagated until the next filter
clock edge, as shown in Figure 6-14.
Not Stable
Digital Input P0.A
Digital Input P0.B
Filter Clock
Filtered Input A
Filtered Input B
Figure 6-14. Case 2
6-27
Chapter 6 Digital I/O
Stable Stable
Not Stable
X Series User Manual