Door Simulator Exercise 2

Hutch463

Member
Join Date
Feb 2011
Location
North Carolina
Posts
2
Hello all! I'm VERY new to PLCs and ladder logic. I'm having a VERY hard time preventing my motor from bursting into flames in Door Simulator Exercise #2. What I have is attached. If it doesn't make sense, it's because I've tried every combination I know of, and lost track a ways back. I'm no far from gouging my eyes out with my pencil. Any hints, subtle pushes, or throwings off a cliff would be appreciated!

Exer 2 Rungs.jpg
 
What events cause it to "burn up".

One problem I do see is if you press the "open" button, it seals in the "up" motor. But, if you then press the "close" button, the up motor seal in is not dropped out. The down motor will enegerize as well, and your motor will start on fire.

Start off by moving the XIO Close and XIO Open to the outside of the branch. If you press the close button while the open motor is running, it will stop running.

As a rule of thumb, when ever I program a machine, any time there are multiple outputs controlling a single actuator like this, which cannot be energized at the same time, I put an XIO of the opposite output as a permissive. Like in the case of a solenoid with two coils, if one coil is turned on, the other cannot be. This way if I make a mistake somewhere in my program and activated the steps in a sequence at the same time, the outputs still won't both come on, and I won't damage my solenoid.
 

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