I am sponsoring a College Senior Design project and the team has reached the mock-up phase. I have tasked them with spec'ing out a hydraulic lift system that would be used for running large drivetrain systems in off-level conditions.

The mock-up phase will be them designing and building a controller that would automate a test sequence. To demonstrate such things as safety features, timing, sequence, etc. they will drive some lamps and maybe a small LCD. For inputs there will be a series of logical inputs to react to, and maybe an analog input or two depending on sensors they choose.

When I was first putting together a requirements document, I was thinking they likely would want to use an Arduino type controller and have various IOs and fulfill the requirements, done. Well, they surprised in our phase kick-off meeting by asking about using a PLC (which they know that we normally use in the lab they toured at our facility.)

So, the question I have is: does anyone have a recommendation for a simple, cost effective PLC module source? Their budget is in the couple hundred dollar range total for the demo-board. Having a SW tool available would also be needed. There is no need for durability, this will used for a demo only and then likely gather dust in my drawer with the other demo projects from previous years.

I am confident they would be able to get through the demo with $100 using Arduino and assorted components. And I have a fair amount of experience working with microcontrollers. But, I just recently learned some PLC things and am intrigued with being able to also learn something while 'advising' them.

I'd estimate that they would need 5-8 inputs and likely the same number of outputs.

Thanks for any thoughts. I did some internet searching, but am afraid I would miss something like "needs $1000 SW tool".

 

Automation Direct offer a cheaper PLC and I believe the S/W is free.
There is also the Mitsubishi FX series on ebay, which I tend to use, I have the S/W if needed.
The advantage of the PLC over Arduino is the ability to display the logic in ladder format for trouble shooting.
There is also the SmartRelay made by a few manuf, but it is a little more limited.
Max.

 

Thanks Max, that Automation Direct website is good, but man there's a lot there. I'll be reading on there for a few hours.

Thanks for the direct reminder of the PLC advantage for this....I am just battling with the balance between that advantage with the demo nature of what I want them to do. Balanced of course with how much time I have to put into this.

They are on spring break next week so I have some time to research these. Thanks again for the quick reply.

 

Have a look at this: https://www.controllino.biz

It might be suitable.

 

Thanks for the direct reminder of the PLC advantage for this....I am just battling with the balance between that advantage with the demo nature of what I want them to do. Balanced of course with how much time I have to put into this.
....asking about using a PLC (which they know that we normally use in the lab.

One advantage is with the PLC you do not have to convert schematic logic into C or..?
Which one do you use in your Lab?
Max.

 

Max, did you look at that Controlino thingy? I think it's really a nice idea.

 

I took a brief look and it showed C programming, does it display in ladder?
Max.

 

I took a brief look and it showed C programming, does it display in ladder?
Max.

A variety of options: https://www.controllino.biz/software/

None appear to be pure ladder logic.

 

One advantage is with the PLC you do not have to convert schematic logic into C or..?
Which one do you use in your Lab?
Max.

Our lab techs are pure ladder diagram programmers. I don't know they exact software they use. However, I likely was not clear enough about the project. The students will be building a small demo-board in their dormroom (our campus lab). They were just suggesting PLC because 1) one of them has some experience with it and 2) Since they know we use it in our lab they thought it would be an advantage to us should we decide to use it. We will not be directly mixing the work in the lab with this demo. It is a standalone, presented to their adviser then given to us along with a copy of their report.

 

One plus for any presentation for a piece of equipment that may require occasional maintenance or trouble shooting is the ability for service personnel to easily recognize or diagnose any problems, and this is where the big advantage with ladder programming as not only does it display the logic in familiar format, it highlights any and all rung functions that are active, and rapidly helps identify the source of said problem.
Also if any changes are to be made, it can usually be done by personnel not familiar with higher level programming methods.
Max.