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4 THE EXCHANGE BETWEEN THE PLC AND BUFFER MEMORY
4.2.3 Choosing a process
4.2.4 Bit/Word designation
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Process requests of PCRD and PCWT instructions are specified using values referred
to as process codes. For details, see the descriptions of the PCRD and PCWT
instructions.
Bit/Word designation refers to the designation of processing in 1-bit units or 1-word
(16-bit) units when the PLC accesses the bit device.
Bit
designation
M0
When word-unit process is specified, 16 bits of process points will be specified. Also,
when word-unit is specified, the starting number of the respective device must be
specified as 0 or a multiple of 16.
Example
For M,
M0, M16, M32,
For B,
B0, B10, B20,
When processing special relay M in word units, the starting number may be 9000
or a multiple of 16 added to 9000.
(M9000, M9016, M9032,
When accessing word devices, use word unit processing.
REMARK
Access • • • I/O processing such as data read and write.
16 points are
Only one point
accessed
is accessed
as a group
• • • •
are used as starting numbers.
• • • •
are used as starting numbers.
............
can be used as starting numbers.)
MELSEC-Q
Word
designation
to
M8 M7
M15
to
M0
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