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Instructions
Description
● Source is the string you want to find when examining the search string.
● Index is the starting position (from 1 to 82) of the source string. (An index of 1 indicates
the left-most character of the string.)
● Search is the string you want to examine.
● Result is an integer where the processor stores the position of the search string where the
source string begins. If no match is found, result is set equal to zero.
ASR
ASCII String Compare
Use the ASR instruction to compare two ASCII strings. The system looks for a match in
length and upper/lower case characters. If two strings are identical, the rung is true; if there
are any differences, the rung is false.
AWT
ASCII Write
Writes a source string to the designated channel. Provides a Result integer for the status of
the write.
Channel 0 = Serial port
Channel 1 = Display
Channel 2 = Ethernet
The internal PLC supports reading from and writing to the Network Ethernet port on the
controllers. Here are the rules:
If Channel ID is set to 2 then the virtual port 8786 will be used.
If a Channel ID >1024 is used then that number is the virtual port used.
Only one virtual port can be used and the first rung in the logic with an ARD or ARW
command with a Channel ID >1024 determines which virtual port will be used.
The Channel ID cannot be set to an address, it must be an integer.
BND
Branch End
Marks the end of a branch.
BST
Branch Start
Marks the beginning of a new branch on a rung.
CLR
Clear
Sets the value of a destination word to zero.
Count Down
Counts false-to-true transitions.
When rung conditions for a CTD instruction have made a false-to-true transition, the
accumulated value is decremented by one count, provided that the rung containing the CTD
instruction is evaluated between these transitions.
The accumulated counts are retained when the rung conditions again become false. The
accumulated count is retained until cleared by a reset (RES) instruction that has the same
address as the counter reset.
Count Down
CTD
Underflow Bit
OV (Bit 11)
Done Bit DN (Bit 13)
This Bit
Accumulated value wraps
around to +32,768 from
-32,767
Accumulated value is equal to
or greater than the present
value
Is Set When
And Remains Set Until One
A RES instruction having the
same address as the CTD
instruction is executed OR the
count is incremented greater
than or equal to +32,767 with
a CTU instruction
The accumulated value
becomes less than the
present value
SC Series Controllers
Embedded PLC
of the Following
105 / 1032
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