Contec ADI12-16(PCI), User Manual

Page: 92 / 95

6. About Hardware
ADI12-16(PCI)
85
Digital Filter
Control signals are filtered with the digital filter at the input pin. The digital filter prevents input
signal noise and chattering.
The digital filter checks the level of the input and, when the input maintains the same signal level for a
certain period of time, regards it as an input signal and changes the signal level of the PC.
If the signal level changes at a faster frequency than that time period, the level change becomes invalid.
Figure 6.5. Digital Filter Operation Principle
Control Signal Delay Time
Control signals involve a delay for "input circuit response time + digital filter wait time."
Input control signals must therefore take account of the delay.
Figure 6.6. Response time
Table 6.3. Control Signal Delay Time
Parameter Symbol Time
Optocoupler response time delay t1 1msec
Waiting digital filter time t2 1msec
Control Signal Delay t1 + t2 2msec
Waiting filter time
Input signal
Input signal
PC input
Valid
Digital
Filter
Invalid
PC input
Input signal
Digital filter input
Digital filter output