Block Memory; Operation Constant - Mitsubishi MELSEC-Q series Programming Manual

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.
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.
(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.
The b0 (BB1) in the block bits stores "1" if any of b1 to b15 (BB2 to BB16) on each instruction stores an alarm data.
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.
Block memory
0 Block word
2 words
(
1
2 Block bit
Process control instruction
Operation result
S.IN
Input data Block word
Block bit
b12
b15
B B B B
B B
B B
Block bit
1 1 1 1
6 5 4 3
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.
Process control instruction
Operation result
S.PHPL
Input data Block word
Transferred by user
b8 b0
b4
B B B B B B B B B B
B B
B B B B B B B B B B B B
1 1 1 9 8 7 6 5 4 3 2 1
2 1 0
Block bit
1
2
3
4
6
6
7
8
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