369
Symbol Math Instructions Section 3-10
Precautions If Mi, Mi +1 and/or Su, Su +1 are not BCD, an error is generated and the Error
Flag will turn ON.
If as a result of the subtraction, the content of R, R +1 is 00000000 hex, the
Equals Flag will turn ON.
If an subtraction results in a borrow, the Carry Flag will turn ON.
Note To clear the Carry Flag (CY), execute the Clear Carry (CLC(041)) instruction.
Examples When CIO 0.01 is ON in the following example, D1101, D1100, and CY will be
subtracted from D1001 and D1000 as 8-digit BCD values, and the result will
be output to D1201 and D1200.
If the result of the subtraction is a negative number (Mi<Su or Mi+1, Mi
<Su+1, Su), the result is output as a 10’s complement. The Carry Flag (CY)
will turn ON. To convert the 10’s complement to the true number, a program
which subtracts the result from 0 is necessary, as an input condition of the
Carry Flag (CY). The Carry Flag turning ON thus indicates that the result of
the subtraction is negative.
Note 10’s Complement
A 10’s complement is the value obtained by subtracting each digit from 9 and
adding one to the result. For example, the 10’s complement for 7556 is calcu-
lated as follows: 9999 – 7556 + 1 = 2444. For a four digit number, the 10’s
complement of A is 9999 – A + 1 = B. To obtain the true number from the 10’s
complement B: A = 10000 – B. For example, to obtain the true number from
the 10’s complement 2444: 10000 – 2444 = 7556.
3-10-17 SIGNED BINARY MULTIPLY: *(420)
Purpose Multiplies 4-digit signed hexadecimal data and/or constants.
Ladder Symbol
Variations
Applicable Program Areas
0.01
D1000
D1100
D1200
*(420)
R
Md
Mr
Md: Multiplicand word
Mr: Multiplier word
R: Result word
Variations Executed Each Cycle for ON Condition *(420)
Executed Once for Upward Differentiation @*(420)
Executed Once for Downward Differentiation Not supported.
Immediate Refreshing Specification Not supported.
Block program areas Step program areas Subroutines Interrupt tasks
OK OK OK OK
To Next Page
Loading...
