Rockwell Automation 2755 Enhanced Decoder Series B - Manual (Page 100)

7–12 Configuration: Scanner Control, Primary Match Table, Discrete I/O
Publication 2755-833
If the filter is enabled, the decoder starts a timer whenever it senses a
package detect signal longer than 1 millisecond. This timer delays
the decoder’s reaction to the package detect for between 10 and 15
milliseconds to allow any “bounce” in the signal level to settle. If the
package detect signal is still present when the timer expires, the
decoder will begin to process the package. Package detect signals
shorter than 10 milliseconds will be ignored by the decoder when
the filter is used. Because of timer resolution, package detects
between 10 and 15 milliseconds may be ignored.
The filter likewise reacts to the loss of the package detect signal.
When the signal is lost for a minimum of 1 millisecond, the filter
will maintain the trigger for 10 to 15 milliseconds. The resultant
trigger period length will be equal to the package detect period
5
milliseconds.
Note: This parameter also applies to Scanner B when operating in
coordinated mode. In coordinated mode, Scanner A and B are
triggered by the same package detect signal (Package Detect Input A
Filter and Package Input A Sense).
Package Detect Input A Sense
Field Type Options
Select
Lo = Package
Hi = Package
Determines whether a package on Scanner Port A is detected when
the voltage at the package detect input is high or low. The default is
LO=Package.
Note: This parameter applies to Scanner B when operating in
coordinated mode. In coordinated mode, Scanner A and B are
triggered by the same package detect signal (Package Detect Input A
Filter and Package Input A Sense).
Package Detect Input B Filter
Field Type Options
Select
Yes
No
Enables or disables the debounce filter for the package detect signal
on Scanner B. The default is No which disables the filter. When
disabled, the decoder recognizes any signal greater than 1
millisecond as a start trigger.