User`s manual

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MELSEC-Q
3 DATA USED FOR PROCESS CONTROL INSTRUCTIONS AND HOW TO
SPECIFY DATA
3.3.3 Block memory
The block memory is an area that stores the output information of the corresponding process
control instruction.
The block memory has "block words" and "block bits".
The application of the block memory changes depending on the used instruction.
Refer to the explanation section of the corresponding instruction.
Block memory
Block word
Block bit
0
1
2
(
2 words
)
2 words are used when real number
is stored into block word.
As block bit, each bit of one word
is used to store ON/OFF data.
Specified device number
(1) Block word (BW)
(a)The block word is an area that stores the operation result of the process control instruction.
(b) As the input data of the next process control instruction linked by the loop, the data stored
in the block word is used.
S.IN S.PHPL
Process control instruction
Input data Block word
Block bit
Process control instruction
Input data
Operation result
Operation resul
t
Transferred by user
Block word
Block bit
(2) Block bit (BB)
The block bit is an area that stores the corresponding alarm data at process control
instruction execution.
As the block bits, 16 bits of b0 to b15 are represented as BB1 to BB16.
b15
b12 b8
b4
b0
B
B
3
B
B
2
B
B
1
B
B
6
B
B
5
B
B
4
B
B
9
B
B
8
B
B
7
B
B
1
2
B
B
1
1
B
B
1
0
B
B
1
5
B
B
1
4
B
B
1
3
B
B
1
6
Block bit
3.3.4 Operation constant
(1) The operation constant is an area that stores the data used by only one process control
instruction.
(2) The application of the operation constant changes depending on the used instruction. Refer to
the explanation section of the corresponding instruction.