Delta DVP-PM Series - Page 175

5 Categories and Use of Basic Application Instructions
DVP-PM Operation Instruction
5-38
API Mnemonic Operands Function
21
D
SUB
P
Subtraction
Controllers
20PM 10PM
Bit Devices Word Devices Program Steps
Type
OP
X Y M S K H KnX KnY KnM KnS T C D V Z
S
1
* * * * * * * * ***
S
2
* * * * * * * * ***
D * * * * * ***
SUB, SUBP: 7 steps
DSUB, DSUBP: 9 steps
Operands:
S
1
: Minuend S
2
: Subtrahend D: Remainder
Explanations:
1. SUB instruction subtracts S
1
and S
2
in BIN format and stores the result in D
2. When SUB is used as 16-bit instruction, Z device cannot be adopted; when SUB is used as 32-bit instruction, V
device cannot be adopted.
3. The MSB is the sign bit. 0 indicates positive and 1 indicates negative. All calculation is algebraically processed
4. Flags:
OX O100
Zero flag M1808 M1968
Borrow flag M1809 M1969
Carry flag M1810 M1970
Flag changes in binary subtraction
In 16-bit DIN subtraction,
a) If the operational result = 0, zero flag will be ON.
b) If the operational result < -32,768, borrow flag will be ON.
c) If the operational result > 32,767, carry flag will be ON.
In 32-bit BIN subtraction,
a) If the operational result = 0, zero flag will be ON.
b) If the operational result < -2,147,483,648, borrow flag will be ON.
c) If the operational result > 2,147,483,647, carry flag will be ON.
5. The operation of flags for ADD instruction can also be applied to SUB instruction.
Program Example 1:
In 16-bit BIN subtraction:
When X0 = ON, the content in D0 will minus the content in D10, and the remainder will be stored in D20.
X0
SUB D0 D10 D20
Program Example 2:
In 32-bit BIN subtraction:
When X1 = ON, the content in (D31, D30) will minus the content in (D41, D40), and the remainder will be stored in
(D51, D50). D30, D40 and D50 are low word; D31, D41 and D51 are high word.
X
1
DSUB D30 D40 D50