Allen-Bradley MicroLogix 1200 Reference Manual page 32

1-16 I/O Configuration
Publication 1762-RM001C-EN-P
Rising Edge Behavior - Example 1
Input
Scan
External
Input
Latched
Status
Input File
Value
Rising 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 rising edge behavior, the input file value is
normally "off" ("on" for 1 scan when a rising edge pulse is
detected).
The previous examples demonstrate rising edge behavior. Falling edge
behavior operates exactly the same way with these exceptions:
• The detection is on the "falling edge" of the external input.
• The input image is normally "on" (1), and changes to "off" (0) for one
scan.
Scan Number (X) Scan Number (X+1)
Ladder Output Input Ladder Output
Scan Scan Scan Scan Scan
Scan Number (X) Scan Number (X+1)
Ladder Output Input Ladder Output
Scan Scan Scan Scan Scan
Scan Number (X+2)
Input Ladder Output
Scan Scan Scan
Scan Number (X+2)
Input Ladder Output
Scan Scan Scan