Subtract (sub), Updates to arithmetic status bits, Entering the instruction – Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) User Manual
Page 171
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Chapter 10
Using Math Instructions
10–5
Use the SUB instruction to subtract one value (Source B) from another
(source A) and place the result in the destination.
Source A and B can either be a word address or a constant, however both
sources cannot be a constant. The destination must be a word address.
Updates to Arithmetic Status Bits
With this Bit:
The Controller:
S0/0
Carry (C)
sets if borrow is generated; otherwise resets.
S0/1
Overflow (V)
sets if underflow; otherwise reset. On underflow, the minor
error flag is also set. The value –32,768 or 32,767 is
placed in the destination. If S2/14 (math overflow selection
bit) is set, then the unsigned, truncated overflow remains in
the destination.
S0/2
Zero (Z)
sets if result is zero; otherwise resets.
S0/3
Sign (S)
sets if result is negative; otherwise resets.
Entering the Instruction
You enter the instruction from within the program monitor functional area.
P 0 0 0
S U B
S R C A
N 1 0
0
P 0 0 0
S U B
S R C B
1 0 0 0
P 0 0 0
S U B
D E S T
N 2 0
0
SUB
SUBTRACT
Source A
N7:10
0
Source B
1000
Dest
N7:20
0
Execution Times (
µ
sec) when:
True
False
33.52
6.78
Ladder representation:
Subtract (SUB)
8
FUN
ENT
To enter the function code, press:
1