Allen-Bradley MicroLogix 1200 Reference Manual page 33

Falling Edge Behavior - Example 1
Scan Number (X)
Input Ladder
Scan Scan
External
Input
Latched
Status
Input File
Value
Falling Edge Behavior - Example 2
Input
Scan
External
Input
Latched
Status
Input File
Value
The "gray" area of the Latched Status waveform is the input
NOTE
filter delay.
The input file value does not represent the external input
IMPORTANT
when the input is configured for latching behavior. When
configured for falling edge behavior, the input file value is
normally "on" ("off" for 1 scan when a falling edge pulse
is detected).
Scan Number (X+1) Scan Number (X+2)
Output Input Ladder Output Input Ladder
Scan Scan Scan Scan Scan Scan
Scan Number (X) Scan Number (X+1)
Ladder Output Input Ladder Output
Scan Scan Scan Scan
I/O Configuration
Scan Number (X+3)
Output Input Ladder Output
Scan Scan Scan Scan
Scan Number (X+2)
Input Ladder Output
Scan Scan Scan Scan
Publication 1762-RM001C-EN-P
1-17