Mitsubishi MELSEC-A series, Programming Manual

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3. INSTRUCTION STRUCTURE
3
−
2
MELSEC-A
(1) Source (S)
1) Source data is used for operation.
2) Source data depends on the device specified as follows:
• Constant …………………… Specify the numeric value used for the
operation. This value is set while the program
is being written and cannot be
changed during run of the program.
• Bit device, word device …... Specify the device which stores the data used
for the operation. Hence, the data must
be stored to the specified device before the
operation is initiated. By changing the data to
be stored to the specified device during
program run, the data used with the instruction
can be changed.
(2) Destination (D)
1) Stores data after operation is performed. When the instruction consists of
instruction part + source device + destination device , the data used for
the operation must be stored to the destination before the operation is
started.
2) The device for storing data must be specified at the destination.
REMARK
1) In this manual, the sources and destination are represented as follows:
Source
…….…. (S)
Source1 ……... (S1)
Source2 ……… (S2)
Destination .…. (D)