Mitsubishi Electric MELSEC iQ-R Series, Programming Manual

Page: 61 / 2110

1 OVERVIEW
1.5 Precautions on Programming
59
1
Operations arising when the OUT, SET/RST, and PLS/PLF
instructions of the same device are used
This section describes the operation when two or more OUT, SET/RST, and PLS/PLF instructions that use the same device
are executed within one scan.
In safety programs executed by the Safety CPU, replace some words as follows:
• "Scan"

"Safety cycle processing"
• "X0"

"SA\X0", "X1"

"SA\X1", "M0"

"SA\M0"
• "END" on the rising edge of X0 (in Figures)

"Safety cycle processing start"
*1
• "END" on the falling edge of X0 (in Figures)

"Safety cycle processing end"
*1
*1 For the PLF instruction, replace "END" with "safety cycle processing start" regardless of the X0 status (rising edge or falling edge).
For OUT instructions of the same device
More than one OUT instruction of the same device must not be issued during one scan.
Otherwise, the specified device turns on or off, depending on the operation result up to each OUT instruction while it is in
execution.
In this case, the device may turn on/off during one scan because the on/off state of the specified device is determined during
execution of each OUT instruction.
The following figure shows the behavior arising when a circuit turning on/off the same internal relay (M0) is created with input
X0 and X1.
If output (Y) is specified using an OUT instruction, the on/off state of the last OUT instruction executed during the one scan will
be output.
(1) Since X0 is on, M0 turns on.
(2) Since X1 is off, M0 turns off.
(3) Since X1 is off, M0 remains off.
(4) Since X1 is on, M0 turns on.
X1 M0
X0 M0
OFF OFF
X1 X1
X0 X0
M0
X1
X0
END END
END
ON ON
OFF OFF
ON ON
ON ON
OFF OFF
M0
M0
M0
M0
(1)
(2)
(3)
(4)