Double Bcd Subtract - Subl(55) - Omron SYSMAC C2000H Operation Manual

BCD Calculations
5-17-8 DOUBLE BCD SUBTRACT – SUBL(55)
Description
Flags
Example
164
Second Subtraction
HR 20
CY
HR 20
CY
In the above case, the program would turn ON HR 2100 to indicate that the
value held in HR 20 is negative.
Ladder Symbols
SUBL(55) @SUBL(55)
Mi
Su
R
When the execution condition is OFF, SUBL(55) is not executed. When the
execution condition is ON, SUBL(55) subtracts CY and the 8-digit contents of
Su and Su+1 from the 8-digit value in Mi and Mi+1, and places the result in R
and R+1. If the result is negative, CY is set and the 10's complement of the
actual result is placed in R. To convert the 10's complement to the true result,
subtract the content of R from zero. Since an 8-digit constant cannot be di-
rectly entered, use the BSET(71) instruction (see Section 5-13-3) to create
an 8-digit constant.
Mi + 1
Su + 1
–
CY R + 1
ER: Mi, M+1,Su, or Su+1 are not BCD.
Indirectly addressed DM word is non-existent. (Content of *DM word
is not BCD, or the DM area boundary has been exceeded.)
CY: ON when the result is negative, i.e., when Mi is less than Su.
EQ: ON when the result is 0.
The following example works much like that for single-word subtraction. In
this example, however, BSET(71) is required to clear the content of DM 0000
0000
–7577
–0
2423 (0000 + (10000 – 7577))
1 (negative result)
Mi: First minuend word (BCD)
IR, SR, AR, DM, HR, TC, LR, #
Su: First subtrahend word (BCD)
Mi
IR, SR, AR, DM, HR, TC, LR, #
Su
R
Mi
Su
CY
R
Section 5-17
Operand Data Areas
R: First result word
IR, AR, DM, HR, LR