Our semi trucks have tarps that close over loads of rock. The tarp actuator motor has a toggle that opens it in one direction and closes in the other. Want to monitor the activity of the switch - if it pushed to open the tarp for say 5 seconds I want it to turn on a red light. If the red light is on and the driver pushes a second switch engaging the hydraulic pump to dump the load I want an alarm to go off. If the tarp switch is pushed to "open" for say five seconds then he can run the hydraulics.
Any ideas on how to do this?
Please provide a block diagram, schemtics, telling the electrical data.
Good help is found in the topic "How to get the best out of this forrum",
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Trucks have nasty electrical systems. Here is some stuff you should read before getting to far into the project.
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Hi, @dbrockdiver1
Welcome to the forum.
Tarp like this;
Tom.... 
from first thoughts, your solution has to consider - electrical, dirt, sunlight, interference and physical factors.
Sure. You're basically saying that if the tarp is in a particular state, then dumping causes an alarm condition. Research "state machines" and the situation will be much clearer.
This problem is an example of a very basic state machine.
As a new user I'm not able to upload a picture or block diagram. Sorry.
Basically, there are two switches on the control box between the seats in the cab. The tarp switch is a SPDT normally off switch. If you push it one direction it sends 12+ volts to a relay on the trailer that then closes and sends 12+ volts high amps to motor on arm that closes the tarp. It takes 30 seconds to close. You have to hold the switch over the whole time. To open the tarp you do the same thing - just push the switch the other direction.
The next switch over is the SPDT switch that runs the relay to the hydraulic cylinder pump. When you want to dump you hold that switch over until the tub dumps and then push it the other direction to drop the cylinder thus the tub goes back to its resting spot.
I want the Ardunio to detect if the tarp close switch has been activated for say 5 seconds - that would set a red light on the box showing the tarp was closed. Then if the driver just before he unloads pushes the tarp switch over to the open position for say 5 seconds then the red light goes out and a green light comes on. All good. But, if the red light is on and the drives hits the hydraulic switch then I need an alarm to go off.
That that helps.
Doug
Yes, you are correct and we constantly fight that at the connection point for the tarp motor on the front of the trailer and the hydraulic pump connections. But in this case I want to connect into the control box in the cab by the driver's seat. Just two switch on/in that box.
Thanks for the response. I will check the state machine info.
Doug
You should be able to; just drag and drop an image in the reply window. You can however not attach a document as a new user.
Well, thats the direct answer to your question.
However it sounds like you really want to know if the tarp is open or closed. That would be better done with a sensor of some type instead of timing the switch.
Hi, @dbrockdiver1
How does the trap controller sense tarp open and tarp closed to operate the existing system?
Tom....
It sounds like the existing "sensor" is the driver's Mk I Eyeball.
There is no controller.
Even though we'd all like there to be one.
@dbrockdiver1 the code is simple enough, your two problems are the harsh environment as @gilshultz points out, and "hijacking" signals off the existing SPDT switch.
Then some coditioning and timing, it can be as complicated as you want or really quite simple.
a7
As cedarlakeinstruments says - the tarp position sensor is the truck driver looking in his mirror at the tarp. There isn't a sensor on the arm that closes the tarp on the trailer. Even if there was it would require another "pigtail" to be run from the tractor to the trailer. Don't want to do that.
I think if I can just read the status of the SPDT switch to see if it is pushed for 5 seconds and use that value to turn of the 'closed' light that should work. Same the other direction - if the switch is held in the 'open the tarp' position for five seconds the green light should come on.
Yeth.
Now provide some details. I could guess.
Show how the SPDT switch connects to power or ground and the relays and how that entire combination, switch and two relays is wired to the vehicle power or wherever the lower for the relays is coming from.
We all hate to see open loop systems, this will be more of a reminder than a fail safe means of "knowing" the tarp is in the correct position. You OK with that then me too.
I'm the beach but I did write a sketch that does what you need using only things you'll need to know about to apply any solutions that are prettier. If it still looks relevant when I get back to the lab I will post it.
But right now one of those days with the azure blue skies and temperatures air and water not to be improved upon and only a gently blowing breeze means don't hold your breath.
You might like to start playing, I use the wokwi simulator and recommend you just start trying the examples in the IDE, wiring a button, lighting up the LED and so forth. Or with real components.
The examples often link to short articles explain things. Read. Read the code and see how it does what it says step by step.
a7
You can post pictures when you get to trust level 1.
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You will probably need to put some limit switches to detect open and closed positions.
