DL205 User Manual, 4th Edition, Rev. B
5–160
Chapter 5: Standard RLL Instructions - Table
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A
B
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D
Source to Table (STT)
The Source To Table instruction moves a value from a
V-memory location into a V-memory table and increments a
table pointer by 1. When the table pointer reaches the end of
the table, it resets to 1. The first V-memory location in the
table contains the table pointer which indicates the next
location in the table to store a value. The instruction will be
executed once per scan provided the input remains on. The
function parameters are loaded into the first level of the
accumulator stack and the accumulator with two additional
instructions. Listed below are the steps necessary to program
the Source To Table function.
Step 1: Load the length of the table (number of V-memory locations) into the firstlevel 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 STT instruction which specifies the source V-memory location (Vaaa). This is where
the value will be moved from.
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 table counter value should be set to indicate the starting point for the
operation. Also, it must be set to a value that is within the length of the table. For example, if
the table is 6 words long, then the allowable range of values that could be in the pointer
should be between 0 and 6. If the value is outside of this range, the data will not be moved.
Also, 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 to 1 automatically when the table length is reached.
aaa
V
STT
ý
ý
ý
þ
230
240
2
5
0
-1
2
6
0
Discrete Bit Flags
Description
SP56
On when the table pointer equals the table length.
Operand Data Type
DL260 Range
aaa
V-memory V
All (See page 3 - 56)
DS
Used
HPP Used
