Pls/Plf Instruction Behavior In The State From Plc Stop To Run - Mitsubishi Electric M800VW Series Programming Manual

M800V/M80V Series PLC Programming Manual (1/2)
6 Explanation of Instructions and Functions

6.9 PLS/PLF Instruction Behavior in the State from PLC STOP to RUN

6.9 PLS/PLF Instruction Behavior in the State from PLC STOP to RUN
PLS instruction turns ON a specified device for one scan when PLS command changes from OFF to ON, and it turns OFF the
specified device in other cases ("OFF to OFF", "ON to ON, or "ON to OFF"). Also, PLF instruction turns ON a specified device
for one scan when the PLF command changes from ON to OFF, and it turns OFF the specified device in other cases ("OFF to
OFF", "OFF to ON, or "ON to ON").
During PLC STOP, you can set to hold or clear the "previous scan state of PLS/PLF instruction" in the bit selection parameter.
This setting is enabled when the PLC is restarted.
#(6456) Data
Use "6456".
Behaviors of PLS instruction are shown below as an example.
Behaviors while "#6456/bit2" (PLS/PLF instruction holding PLC in STOP state valid) is set to "0"
Clear "previous scan state of PLS/PLF instruction" at PLC STOP.
When RUN is executed from PLC STOP again, PLS/PLF instruction is executed with the cleared state of "previous scan sate
of PLS/PLF instruction". Therefore, even if the contact point of PLS instruction is ON at PLC STOP, the device of one scan
PLS instruction argument turns ON when RUN is executed from PLC STOP.
[Ladder]
X0
PLS M0
IB-1501667-B
7 6 5 4 3 2 1 0 ←Bit
( 0 0 0 0 0 1 0 0 )
0 : Clear the previous scan state of PLS/PLF
instruction at PLC STOP.
1 : Hold the previous scan state of PLS/PLF
instruction at PLC STOP.
[Timing chart]
X0
END
ON
X0
ON
M0'
M0 OFF
(Saves PLS
instruction status)
M0 remains OFF because
M0' = ON -> X0 = ON.
M0' saves X0 = OFF at the
same time.
118
X0
PLS M0
PLC
PLC
STOP RUN
END
M0' is
turned OFF
ON
ON
M0 turns ON because
M0' = ON -> X0 = ON.
M0' saves X0 = ON at the
same time.
PLS M0
END