Delta AH500 - Page 203

AH500 Programming Manual
5-24
Instruction code Operand Function
FB_PN
S
The circuit is falling edge-triggered.
Device
DX DY X Y M SM S T C HC D L PR
S
●
●
●
●
●
●
●
●
●
●
●
Symbol:
S
：
For internal use Bit
Explanation:
1. When the value in the accumulative register turns from 1 to 0, the instruction FB_PN keeps the
value 1 in the accumulative register for a scan cycle. After the second scan cycle is finished,
the value in the accumulative register changes to 0.
2. The previous state of the contact is stored in the bit device S. Please do not use S repeatedly
in the program. Otherwise, the wrong execution result will appear.
3. The instruction FB_PN only can be used in the function block.
Example:
Instruction: Operation:
LD
M0
Contact A of M0 is loaded.
AND
M1
Contact A of M1 is connected in series.
FB_PN
D0.0
The circuit is falling edge-triggered.
OUT
Y0.0
The coil Y0.0 is driven.
Timing diagram:
One scan cycle
M0
Y0.0
M1
One scan cycle