Mitsubishi Electric M800VW Series Programming Manual page 138

M800V/M80V Series PLC Programming Manual (1/2)
6 Explanation of Instructions and Functions
6.8 Operations When the OUT, SET/RST, or PLS/PLF Instruction of the Same Device is Used
When the PLS/PLF instruction of the same device is used
The PLS instruction turns a specified device ON when the PLS command changes from OFF to ON, and it turns a specified
device OFF when the PLS command changes in a way other than "from OFF to ON" (which means from OFF to OFF, ON to
ON, or ON to OFF). Also, the PLF instruction turns a specified device ON when the PLF command changes from ON to OFF,
and it turns a specified device OFF when the PLF command changes in a way other than "from ON to OFF" (which means
from OFF to OFF, OFF to ON, or ON to ON).
When the PLS/PLF instruction of the same device is executed several times in one scan, the operation behaviors are as
follows.
 When the execution command of each PLS instruction is from OFF to ON, it turns ON the specified device.
When the execution command of each PLS instruction is other than from OFF to ON, it turns OFF the specified device.
 When the execution command of each PLF instruction is from ON to OFF, it turns OFF the specified device.
When the execution command of each PLF instruction is other than from ON to OFF, it turns OFF the specified device.
Thus, when the PLS/PLF instruction is executed several times in one scan, note that the operation may not be carried out in a
way as expected by the PLS/PLF instruction. (The turned ON device commanded by PLS/PLF instruction may not turn ON for
one scan.)
[Ladder]
X0
PLS M0
X1
PLF M0
[Timing chart]
X0
END
OFF
X0
ON
OFF
X1
ON
M0 OFF
M0 turns OFF because X0
is other than ON -> OFF.
M0 turns ON because
X0 is OFF -> ON.
117
X0
PLS M0
X1
X1
PLF M0
END
ON
M0 turns ON because
X0 is ON -> OFF.
M0 turns OFF because X0 is
other than ON -> OFF.
PLS M0
PLF M0
END
IB-1501667-B