AutomationDirect DL205 - Page 382

DL205 User Manual, 4th Edition, Rev. D
5-158
Chapter 5: Standard RLL Instructions
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A
B
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D
In the following example, when X1 is on, the constant value (K6) is loaded into the accumulator
using the Load instruction. This value specifies the length of the table and is placed in the first
stack location after the Load Address instruction is executed. The octal address 1400 (V1400)
is the starting location for the source table and is loaded into the accumulator. Remember,
V1400 is used as the pointer location, and is not actually part of the table data source. The
destination location (V1500) is specified in the Remove From Bottom. The table pointer
(V1400 in this case) will be decremented by “1” after each execution of the RFB instruction.
It is important to understand how the table locations are
numbered. If you examine the example table, you’ll notice
that the first data location, V1401, will be used when the
pointer is equal to one. The second data location, V1402,
will be used when the pointer is equal to two, etc.
Also, our example uses a normal input contact (X1) to
control the execution. Since the CPU scan is extremely
fast, and the pointer decrements automatically, the table
would cycle through the locations very quickly. If this is a
problem for your applicaton, you have an option of using
a one-shot (PD) to remove one value each time the input
contact transitions from low to high.
X1
Handheld Programmer Keystrokes
STR
$
SHFT
ANDST
L
3
D
SHFT
ORN
R
5
F
1
B
PREV
1
B
ENT
6
G
0
A
0
A
ENT
SHFT
ANDST
L
3
D
1
B
4
E
0
A
ENT
0
A
1
B
5
F
0
A
ENT
LD
K6
LDA
0 1400
RFB
V1500
Load the constant value 6
(HEX) into the lower 16 bits
of the accumulator
Convert octal 1400 to HEX
300 and load the value into
the accumulator. This is the
table pointer location
Copy the specified value from
the table to the specified
destination (V1500)
DirectSOFT
V1401
050 0
V1402 999 9
V1403
307 4
V1404
898 9
V1405
101 0
V1406
204 6
V1407
XXX X
S
S
V150
0
XXX X
1
2
3
4
5
6
Destination
V140
0
000 0
Tabl ePoi nterTable
LD
K6
C0
X1 C0
PD
Load theconstant value6
(HEX) into thelow er 16 bits
of theaccumulator
LDA
O 1400
Convertoctal 1400 to HEX
300 and load theval ue into
theaccumulator. This is the
table pointer location.
LD
K6
C0
X1 C0
PD
Load theconstant value6
(HEX) into thelow er 16 bits
of theaccumulator
LDA
O 1400
Convertoctal 1400 to HEX
300 and load theval ue into
theaccumulator. This is the
table pointer location.
DirectSOFT (optional one-shot method)