AutomationDirect DL205 - Page 378

DL205 User Manual, 4th Edition, Rev. D
5-154
Chapter 5: Standard RLL Instructions
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Table to Destination (TTD)
The Table To Destination instruction moves a value from a
V-memory table to a V-memory location and increments the
table pointer by 1. The first V-memory location in the table
contains the table pointer which indicates the next location in
the table to be moved. The instruction will be executed once
per scan provided the input remains on. The table pointer will
reset to 1 when the value equals the last location in the table.
The function parameters are loaded into the first level of the
accumulator stack and the accumulator by two additional
instructions. Listed below are the steps necessary to program the
Table To Destination function.
Step 1: Load the length of the data table (number of V-memory locations) into the first level of the
accumulator stack. This parameter must be a HEX value, 0 to FF.
Step 2: Load the starting V-memory location for the table into the accumulator. (Remember, the
starting location of the table is used as the table pointer.) This parameter must be a HEX
value.
Step 3: Insert the TTD instruction that specifies the destination V-memory location (Vaaa).
Helpful hint: For parameters that require HEX values when referencing memory locations, the
LDA instruction can be used to convert an octal address to the HEX equivalent and load the
value into the accumulator.
Helpful hint: The instruction will be executed every scan if the input logic is on. If you do not
want the instruction to execute for more than one scan, a one shot (PD) should be used in the
input logic.
Helpful hint: The pointer location should be set to the value where the table operation will
begin. The special relay SP0 or a one shot (PD) should be used so the value will only be set in
one scan and will not affect the instruction operation.
NOTE: Status flags (SPs) are only valid until:
— another instruction that uses the same flag is executed, or
— the end of the scan.
The pointer for this instruction starts at 0 and resets when the table length is reached. At first glance it
may appear that the pointer should reset to 0. However, it resets to 1, not 0.
TTD
aaaV
TTD
aaa
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


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250-1
260
Discrete Bit Flags Description
SP53 On if there is no value in the table that is equal to the search value.
Operand Data Type DL260 Range
aaa
V-memory V All (See page 3 - 56)
DS Used
HPP Used