AutomationDirect DL205 - Page 338

DL205 User Manual, 4th Edition, Rev. D
5-114
Chapter 5: Standard RLL Instructions
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A
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Subtract Top of Stack (SUBS)
Subtract Top of Stack is a 32-bit instruction that subtracts
the BCD value in the first level of the accumulator stack from
the BCD value in the accumulator. The result resides in the
accumulator. The value in the first level of the accumulator
stack is removed and all stack values are moved up one level.
NOTE: Status flags are valid only until another instruction uses the same flag.
In the following example, when X1 is on, the value in V1400 and V1401 will be loaded into
the accumulator using the Load Double instruction. The value in V1420 and V1421 is loaded
into the accumulator using the Load Double instruction, pushing the value previously loaded
into the accumulator onto the accumulator stack. The BCD value in the first level of the
accumulator stack is subtracted from the BCD value in the accumulator using the Subtract
Stack instruction. The value in the accumulator is copied to V1500 and V1501 using the Out
Double instruction.
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240
250-1
260
SUBS
Discrete Bit Flags Description
SP63 On when the result of the instruction causes the value in the accumulator to be zero
SP64 On when the 16-bit subtraction instruction results in a borrow
SP65 On when the 32-bit subtraction instruction results in a borrow
SP70 On anytime the value in the accumulator is negative
SP75 On when a BCD instruction is executed and a NON-BCD number was encountered
LDD
V1400
X1 Load thevalue in V1400 and
V1401 into theaccumulator
LDD
V1420
Load thevalue in V1420 and
V1421 into theaccumulator
OUTD
V1500
Copy thevalue in the
accumulatortoV1500
and V1501
XXXXXXXXLevel 1
XXXXXXXXLevel 2
XXXXXXXXLevel 3
XXXXXXXXLevel 4
XXXXXXXXLevel 5
XXXXXXXXLevel 6
XXXXXXXXLevel 7
XXXXXXXXLevel 8
00172056Level 1
XXXXXXXX
Level 2
XXXXXXXXLevel 3
XXXXXXXX
Level 4
XXXXXXXXLevel 5
XXXXXXXX
Level 6
XXXXXXXXLevel 7
XXXXXXXX
Level 8
SUBS
Subtract thevalue in thefirst
levelofthe accumulator
stackfromthe valueinthe
accumulator
Acc.
V1400
2 056
0017 2056
V1401
0017
Acc.
V1420
5 026
0039 5026
V1421
0039
Accumulatorstack
after1st LDD
Accumulatorstack
after 2nd LDD
Acc.
0022 2970
0022 2970
Handheld Programmer Keystrokes
SHFT
ANDST
L
3
D
STR
$
SHFT
ISG
U
1
B
OUT
GX
SHFT
3
D
1
B
5
F
0
A
0
A
ENT
1
B
ENT
1
B
4
E
0
A
0
A
ENT
ENT
SHFT
ANDST
L
3
D
1
B
4
E
2
C
0
A
ENT
3
D
RST
S
3
D
RST
S
SHFT
V1501 V1500
DirectSOFT
DS Used
HPP Used