AutomationDirect DL105, Руководство пользователя

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Standard
RLL
Instructions
5--13
Standard RLL Instructions
Boolean Instructions
DL105 PLC User Manual, 3rd Edition
There are limits to what you can enter with boolean instructions. This is because the
DL105 internal CPU uses an 8-level stack to evaluate the various logic elements.
The stack is a temporary storage area that helps solve the logic for the rung. Each
time you enter a STR instruction, the instruction is placed on the top of the stack. Any
other instructions on the stack are pushed down a level. The And Store and Or Store
instructions combine levels of the stack when they are encountered. Since the stack
is only eight levels, an error will occur if the CPU encounters a rung that uses more
than the eight levels of the stack.
The following example shows how the stack is used to solve boolean logic.
X1 OR (X2 AND X3)
STR X0 STR X1 STR X2
1 STR X0
2
3
4
5
6
7
8
1 STR X1
2 STR X0
3
4
5
6
7
8
1 STR X2
2 STR X1
3 STR X0
4
5
6
7
8
AND X3
1 X2 AND X3
2 STR X1
3 STR X0
4
5
6
7
8
ORST
1
2
STR X0
3
8
OUT
Y5 X0 X1
X2 X3
X4
X5
STR
OR
AND
ORST
ANDST
Output
STR
STR
AND
X4 AND [X1 OR (X2 AND X3)]
AND X4
1
2
STR X0
3
8
X5 OR [X4 AND [X1 OR (X2 AND X3)]]
OR X5
1
2
STR X0
3
8
ANDST
X0 AND [(X5 OR [X4) AND [X1 OR (X2 AND X3)]]] 1
2
3
8