maax555
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Quick regarding capabilities.

Mon Sep 12, 2016 10:05 am

Hi all, I work for a company that manufacturer wiring looms and control boxes for the automotive sector. We recently commissioned a company to produce a test rig to test a control box. The cost ended up being a massive 4k which was mainly due to the hardware they used. I am not too familiar with Raspberry Pi but have heard a little about it and seen various kits available. This got me thinking would it be possible to use a Raspberry Pi system to test a control box?

Basically the control box is run from 12v. it has a couple of switches which operate relays and then output to a 12 way connector.
Also a couple of inputs are required through same connector.

So the test unit would need to be able to output 12v at a given time delay or press of a button on a specific output (many individual outputs would be needed for larger projects). It would also have to receive inputs of 12V. I think it would be useful to use logic gates, can Pi do this. When the unit detects a fault it would alert the user and when the control box passes the tests it would have the ability to print a label which would be pre programmed into Pi. Finally I would love to run it through one of the 7" touchscreens. Does any of this sound at all possible and is the Pi unit programmed from a PC?

Any comments appreciated.

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CarlRJ
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Re: Quick regarding capabilities.

Mon Sep 12, 2016 6:13 pm

The Pi is not programmed from a PC, it is the heart of a standalone Linux-based computer itself. One can certainly use PC's while programming the Pi (I usually ssh into my Pi's from a Mac).

The Pi is not directly capable of working with 12 volt power (nor will it run on 12v - it requires nice clean 5v power, but an appropriate adapter could convert one to the other), though it could control relays (or similar) that, in turn, controlled 12 volt power.

The Pi has a connector on it that has many "GPIO" (General Purpose Input/Output) pins that can be controlled through software, used as either digital inputs or digital outputs. And it likely has enough speed to run whatever test patterns you need. Indeed, it's possible you could run the test patterns you need from a $10 microcontroller (an "Arduino" in common parlance, though actual Arduino boards cost more) rather than a $35 Raspberry Pi.

However, the most expensive part, by far, of a system like you describe, is generally the software needed to make it run. If you are a skilled software developer with a lot of experience, then developing such a system on your own would not be terribly difficult, but given the details of your description, I'm guessing you'd need to contract out the software development, and it'd probably cost as much or more than your current test rig. Though if you then owned the full rights to the resulting program, you could construct additional test rigs for the modest cost of the hardware parts involved.

maax555
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Joined: Mon Sep 12, 2016 9:47 am

Re: Quick regarding capabilities.

Mon Sep 12, 2016 6:27 pm

Hi Carl, many thanks for your reply. I think I may have misunderstood the purpose of the Pi? I thought it was an expandable modular system which could be easily programmed with a little practice and knowledge. I kind of envisaged a PC program where you could graphically build a program from preset functions and create your own custom ones. Looks like I will go a different route. A little disappointed as love techy stuff and electroics.

W. H. Heydt
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Re: Quick regarding capabilities.

Mon Sep 12, 2016 6:49 pm

maax555 wrote:Hi Carl, many thanks for your reply. I think I may have misunderstood the purpose of the Pi? I thought it was an expandable modular system which could be easily programmed with a little practice and knowledge. I kind of envisaged a PC program where you could graphically build a program from preset functions and create your own custom ones. Looks like I will go a different route. A little disappointed as love techy stuff and electroics.
It sounds like you are thinking more along the lines of a microcontroller board, like an Arduino.

Heater
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Re: Quick regarding capabilities.

Mon Sep 12, 2016 6:54 pm

4K is cheap. I assume you are talking dollars.

Let's say that when you "commissioned a company to produce a test rig to test a control box" the cost of the hardware involved was zero. And the operating system and other required software.

Still that leaves you with a bill of nearly 4K.

Why? Because somebody had to design it, build it, test it. They get a salary. The company they work for wants a profit. They have to pay rent and taxes and whatever else.

OK. Let's say you do it yourself. With a cheap Pi or whatever. Again the hardware cost is essentially zero. BUT your company will have to pay you for the time it takes to develop a solution? How long will that take? What is your salary?

Well, perhaps, if you have noting better to be doing for them at the time it makes economic sense.

Do the sums yourself. Does it add up ?
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CarlRJ
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Re: Quick regarding capabilities.

Mon Sep 12, 2016 8:16 pm

maax555 wrote:Hi Carl, many thanks for your reply. I think I may have misunderstood the purpose of the Pi? I thought it was an expandable modular system which could be easily programmed with a little practice and knowledge. I kind of envisaged a PC program where you could graphically build a program from preset functions and create your own custom ones. Looks like I will go a different route. A little disappointed as love techy stuff and electronics.
The Pi can be expanded and is very adaptable to new hardware. And it can be easily programmed. There are visual programming systems like you describe (Scratch is one), but they're primarily designed to teach students how to program, not to write production-ready code to use on an assembly line. I highly recommend getting a Pi and learning how to code - it's a great skill to have in general, and helps with understanding what programmable machines are capable of, and you may eventually create the system you want, but don't expect to buy a Pi today and put it on your production floor tomorrow, or next week, or next month.

Part of my concern is you're talking about building wiring harnesses for cars - something where the testing has to be very thorough and reliable, because mistakes that slip through can cause serious safety issues. As such, a program for testing these wiring harnesses should not be the first code you write. I don't know of any system currently available that would let you choose bits to glue together to make something ready to run on an assembly line. There are likely companies out there who have developed systems kind of like that in-house, that they can use to create custom test rigs for you, but the rigs won't come cheap (as you've discovered), and the companies are highly unlikely to be willing to sell you the tools they use to develop the rigs (I worked for many years on specialized payroll software for the movie&TV industry - the company I worked for would cheerfully do your show's payroll, using their highly customized software, but they would never even consider the idea of selling the software itself - that'd be giving away their key advantage).

I apologize if I sound harsh, I don't mean it like that. Get a Pi. Experiment with it. Learn what it can do, and discover the joys of programming. Come back and ask questions when you get stuck, and we'll help you over the hurdles.

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DougieLawson
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Re: Quick regarding capabilities.

Mon Sep 12, 2016 9:02 pm

If you assume they're charging $100 per hour (and that's not unreasonable), your $4000 buys a week of someone's time. It's still reasonable even if they're building test rigs every day of the year and selling the same basic item to every customer, your $4000 is for your customisation. That's before you look at licencing, warranty and support.

When I worked for IBM United Kingdom Ltd. (full time, on a fixed salary) they would charge my time at about £2500 (approx $4000) per day (for an eight hour day). I got a small slice of that for my salary.
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henryhanselscott
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Re: Quick regarding capabilities.

Tue Sep 13, 2016 9:22 am

Just for clarity, the pi is TOTALLY capable to of everything that you listed. You will have peripheral support hardware such as relays and input levelers. Also, it will not be a "drag and drop" programming experience. But is is very much a worth while endeavor if your current jog scope allows for something like this. 4K is not out of line for a custom device, the question you need to ask yourself is if you want to greatly increase your skill set in the marketplace. The knowledge already contained in this forum could get you where you need to go, you would just have to be dedicated to the task.

Henry

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