Mitsubishi Electric MELSEC iQ-R Series User Manual page 23

Timing to perform the access control
The following figure shows the timing chart of the access control on input data areas.
'PN to CPU handshake flag
(data consistency setting input area)'
(Un\G17128 to Un\G17135)
'CPU to PN handshake flag
(data consistency setting input area)'
(Un\G17041 to Un\G17048)
Reading out input data by
the CPU module
Input data area
Control by the RJ71PN92
Control by a program
Precautions
When creating a program to read input data, follow the precautions below.
• When the bits of 'CPU to PN handshake flag (data consistency setting input area)' (Un\G17041 to Un\G17048) and 'PN to
CPU handshake flag (data consistency setting input area)' (Un\G17128 to Un\G17135) corresponding to the IO device that
exchanges the I/O data are both off or on, the consistency of input data is not ensured. When input data is read while the
bits are both off or on, the input data before the update may be read.
• After data is read from the input data areas, reverse the on/off state of the bit of 'CPU to PN handshake flag (data
consistency setting input area)' (Un\G17041 to Un\G17048) corresponding to the IO device that exchanges the I/O data.
(On  Off or Off  On) If the on/off state of this bit is not reversed, the input data areas are not updated.
ON
OFF
ON
OFF
Prohibited Allowed
0
Update
OFF→ON
Comparing
the status
Prohibited Allowed
1 2
Update
ON→OFF
Comparing
Read out
the status
OFF→ON
Prohibited
3
Update
OFF→ON
Read out
ON→OFF
1 FUNCTIONS
1.2 Data Consistency Function
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