Add Safety Light Feature; Modify The Block Diagram And State Diagram - Automation Direct DL05 User Manual

Chapter 7: RLL
PLUS

Add Safety Light Feature

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Next we will add a safety light feature to the door
opener system. It's best to get the main function
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working first as we have done, then adding the
secondary features.
3
The safety light is standard on many commercially-
available garage door openers. It is shown to the
right, mounted on the motor housing. The light
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turns on upon any door activity, remaining on for
approximately 3 minutes afterwards.
5
This part of the exercise will demonstrate the use of
parallel states in our state diagram. Instead of using
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the JMP instruction, we'll use the set and reset
commands.
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Modify the Block Diagram and State Diagram

To control the light bulb, we add an output to our
controller block diagram, shown to the right, Y3 is the
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light control output.
In the diagram below, we add an additional state
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called "LIGHT". Whenever the garage owner presses
the door control switch and releases, the RAISE or
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LOWER state is active and the LIGHT state is
simultaneously active. The line to the Light state is
dashed, because it is not the primary path.
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We can think of the Light state as a parallel process to the raise and lower state. The paths to
the Light state are not a transition (Stage JMP), but a State Set command. In the logic of the
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Light stage, we will place a three-minute timer. When it expires, timer bit T0 turns on and
resets the Light stage. The path out of the Light stage goes nowhere, indicating the Light stage
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just becomes inactive, and the light goes out!
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A
B
C
D
7–12
DL05 Micro PLC User Manual, 6th Edition, Rev. A
Stage Programming
X0
DOWN
X2
Inputs
Toggle
Up limit
Down limit
Output equations:
X0
RAISE
Push–UP
X0
LIGHT
X0
LOWER
Push–DOWN
X0
Safety light
Outputs
X0 Y1
X1 Y2
X2 Y3
Y1 = RAISE
Y2 = LOWER
Y3 = LIGHT
X1
UP
T0
X0
Raise
Lower
Light