Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 137)

Using Math Instructions
8–5
Subtract (SUB)
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 constant.
Updates to Arithmetic Status Bits
With this Bit: The Controller:
S:0/0 Carry (C) sets if borrow is generated; otherwise resets.
S:0/1 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 S:2/14 (math overflow selection bit) is set,
then the unsigned, truncated overflow remains in the
destination.
S:0/2 Zero (Z) sets if result is zero; otherwise resets.
S:0/3 Sign (S) sets if result is negative; otherwise resets.
Programming
Execution Times
(
µ
sec) when:
True False
33.52 6.78
SUB
SUBTRACT
Source A
Source B
Dest