Measurement Computing WBK17 - Manual (Page 7)

WBK17, Counter/Encoder Module 987996 WBK17, pg. 7
Debounce Module
Each channel’s comparator output can be debounced with 16 programmable debounce times from
500 ns to 25.5 ms. The debounce module eliminates switch-induced transients typically associated with
electro-mechanical devices including relays, proximity switches, and encoders.
From the following illustration we can see that there are two debounce modes, as well as a debounce
bypass. In addition, the signal from the comparator can be inverted before it enters the debounce circuitry.
The inverter is used to make the input rising-edge or falling-edge sensitive.
Edge selection is available with or without debounce. In this case the debounce time setting is ignored and
the input signal goes straight from the inverter [or inverter bypass] to the counter module.
There are 16 different debounce times. In either debounce mode, the debounce time selected determines
how fast the signal can change and still be recognized.
The two debounce modes are “trigger after stable” and “trigger before stable.” A discussion of the two
modes follows.
Debounce Model