Delta Electronics EXIO14RAE - Page 112

Appendix D Use of Application Instructions|DOP-EXIO Series
Revision March, 2008, Doc. Name: 2007PDD23000014 D-31
Mnemonic Operands Function
SUB D
S
1
S
2
D
Subtraction
Bit Devices Word Devices
X Y M S K H KnX KnY KnM KnS T C D E F
S
1
          
S
2
          
D
       
y Note:
1. If S
1
, S
2
and D are used in device F, only 16-bit instruction is
applicable.
16-bit instruction (7 Steps)
SUB
Continuous
execution
32-bit instruction (13 Steps)
DSUB
Continuous
execution
y Flags: M1020 (Zero flag)
M1021 (Barrow flag)
M1022 (Carry flag)
Operands:
S
1
: Minuend
S
2
: Subtrahend
D
: Remainder
Explanations:
1. This instruction subtracts S
1
and S
2
in BIN format and stores the result in D.
2. The highest bit is symbolic bit 0 (+) and 1 (-), which is suitable for algebraic subtraction.
3. Flag changes in binary subtraction
In 16-bit instruction:
a) If the operation result ＝ 0, zero flag M1020 = On.
b) If the operation result ＜ –32,768, borrow flag M1021 = On.
c) If the operation result ＞ 32,767, carry flag M1022 = On.
In 32-bit instruction:
a) If the operation result ＝ 0, zero flag M1020 = On.
b) If the operation result ＜ –2,147,483,648, borrow flag M1021 = On.
c) If the operation result ＞ 2,147,483,647, carry flag M1022 = On.
4. For flag operations of SUB instruction and the positive/negative sign of the value, see the
explanations in ADD instruction on the previous page.
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 X10 = 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 16-bit data; D31, D41 and D51 are high 16-bit
data.