3. INSTRUCTION STRUCTURE
3
−
7
MELSEC-A
When the range of numeric values handled in 16 bits and 32 bits exceeds that
specified (overflow, underflow) this is indicated as in the following table.
Table 3.3 processing Outside the Allowed Numeric Value Range
Processing of 16-bit Data
Processing of 32-bit Data
Decimal display
Hexadecimal display
Decimal display
Hexadecimal display
Overflow
8003
H
8002
H
8001
H
8000
H
7FFF
H
7FFE
H
7FFD
H
7FFC
H
80000003
H
80000002
H
80000001
H
80000000
H
7FFFFFFF
H
7FFFFFFE
H
7FFFFFFD
H
7FFFFFFC
H
Processing of 16-bit Data
Processing of 32-bit Data
Decimal display
Hexadecimal display
Decimal display
Hexadecimal display
Underflow
8003
H
8002
H
8001
H
8000
H
7FFF
H
7FFE
H
7FFD
H
7FFC
H
80000003
H
80000002
H
80000001
H
80000000
H
7FFFFFFF
H
7FFFFFFE
H
7FFFFFFD
H
7FFFFFFC
H
Even in the case of overflow and underflow, the carry flag and error flag do not
change.
Decimal display corresponds to hexadecimal display as shown below.
Decimal display
Hexadecimal display
5
4
3
2
1
0
–1
–2
–3
–4
–5
-32768
0005
H
0004
H
0003
H
0002
H
0001
H
0000
H
FFFF
H
FFFE
H
FFFD
H
FFFC
H
FFFB
H
8000
H
POINT
To use values 32768 and over or -32769 and below in decimal notation, use
32-bit data for processing.
Over
flow
–32765
–32766
–32767
–32768
32767
32766
32765
32764
……
Over
flow
–2147483645
–2147483646
–2147483647
–2147483648
2147483647
2147483646
2147483645
2147483644
Under
flow
–32765
–32766
–32767
–32768
32767
32766
32765
32764
Under
flow
–2147483645
–2147483646
–2147483647
–2147483648
2147483647
2147483646
2147483645
2147483644
……
……
……
~
~
Summary of Contents for MELSEC-A series
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