Rockwell Automation 440C Guardmaster 440C-CR30 Configurable Safety Relay User Manual - Manual (Page 39)

Rockwell Automation Publication 440C-UM001C-EN-P - November 2014 39
Chapter
6
Input Filter
Input filtering gives the CR30 the ability to filter out noise and, in some cases,
inadvertent operation.
Sometimes, an operator presses a push button and immediately realizes that they
pressed the wrong button and immediately releases the button. In muting
applications, an object, moving down a conveyor, might stop just at the point
where the muting sensor is deactivated and then back off enough that the muting
sensor is reactivated.
When an input filter time (t1) is specified, an input channel is allowed to go to
the LO state while the other channel is in the HI state for that length of time
without the output of the instruction going to the LO state. However, the output
goes to the LO state when both input channels are in the LO state
simultaneously. The input filter operates on both the leading edge and trailing
edge of the input signals. If specified, the filter time must be included in the
response time calculation.
Figure 23 - Input Filtering
Input filtering can set in 25 ms increments, from 0…1000 ms. The default value is
0 ms.
Channel A
Channel B
Output
t1
1
0
0
0
1
1
t1
t1 t1