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Use trigger before stable mode when the input signal has groups of glitches and each group is to be
counted as one. The trigger before stable mode will recognize and count the first glitch within a group but
reject the subsequent glitches within the group if the debounce time is set accordingly. The debounce time
should be set to encompass one entire group of glitches as shown in the following diagram.
Trigger after stable mode behaves more like a traditional debounce function: rejecting glitches and only
passing state transitions after a required period of stability. Trigger after stable mode is used with electro-
mechanical devices like encoders and mechanical switches to reject switch bounce and disturbances due to
a vibrating encoder that is not otherwise moving. The debounce time should be set short enough to accept
the desired input pulse but longer than the period of the undesired disturbance as shown in the diagram
below.
5-4 Counter Input Modes 918494 DaqBoard/3000 Series User’s Manual