xtal_01

Cheap plc .... any good ones?

16 posts in this topic

Hello,

I have built custom control panels for about 20 years.  Most of my clients still prefer "relay logic" as even a tech in the field with knowledge can repair them .. no need for a pc or special training (and they don't have to pay me to come out into the field).

The other clients I have done work for all had a "factory standard" and so I had to stay with their brand of PLC.  For example, my last contract position (I was told there was 6 months work ... I stayed for 10 years finally leaving to take a full time job with the company) used GE.  The place I worked for the 5 years previous only used Allen Bradly.

Anyway, I actually have a "home" project for a change!  After three years of living onsite in an RV while building (well freezing here in VT when temperatures hit -30) my wife and I moved into the lower unfinished level of our new home.  My problem is I need an elevator as my wife is paralyzed from the shoulders down (diving accident when she was 12 ... she is 37 now).  We thought we had this taken care of when we started building.  We got two quotes ... both for around $15K.  We found a grant for $10K so about $5K out of pocket.  Now three years later both companies came in with new quotes of about $40K ... way out of our budget!

So, I purchased an electric forklift (30 years old but working great .... $850).  I stripped off the mast, pump and motor.  The mast is in place, I am building a "car" to fit on top of the forks.  I have designed a complete hydraulic power unit.  In order to get rid of the "jerk" when starting and stopping, I purchased a flow control valve and control board (can take 0-5, 0-10 or 4-20).  I have numerous interlocks to check position, to open, close and lock gates (preventing entry when the car is not at the right location), I have over travel switches (hooked to a contactor and not just the PLC), even a timer to prevent the motor from continuously running if a contactor welds itself on (saw a forklift start on fire because of this once).  I even have a back-up hydraulic pump (plus the main pump is running of 24 volt batteries so it will function even if the power goes out).

So, now it is time for controls.  We are on a super tight budget (who isn't).  I will need to buy a plc with digital I/O and an analog output and software.  I will probably even have a PC dedicated to it so if it needs maintenance even 15 years from now, I won't have to worry about finding a PC compatible with 15 year old software.  Brands like Allen Bradly are just out of reach for a home project ... I can't even afford the software.

I had been looking at plc's from Automation Direct.  They seem reasonably priced ... but then I read the reviews ... some great, some bad!  There may be others but I don't know of anyone personally who has tried any of these.

Can anyone suggest a "cheap" brand of PLC that is "good"?

I would even consider converting a PC for use as a PLC (using one of the small industrial ones with a solid state hard drive) and putting the I/O off the USB port but again, I don't know of anyone with personal knowledge of this to see if it is "good" or not.

I would appreciate any advice!

Thanks ...... Mike

PS ... I have been building panels in the unfinished part of the house while we built ... the pad is poured for the new shop ... work starts this spring.  I have included a picture of a "typical" relay logic panel I build (built this one while moving).  You can also see pictures of the RV I converted (long story but my wife needs care every 4 hours so I converted an RV so she could travel) at http://mcsele.shutterfly.com/2299   .... I designed an build a lift that folds under the RV, a lift on the inside, installed hospital beds, ......

 

P01.jpg

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I have used the Teco SG2 PLR for a few panels and have never had any failures with them. They are similar to but a little bit less expensive than the Idec units. Their tech support is not great, but that's to be expected with a cheap controller. Their analog I/O module has a very limited analog ramp capability (4 fixed steps), but probably enough for what you are doing.

http://www.factorymation.com/Products/Programmable_Controllers/

The other alternative would be a low end "brick" PLC like the A-D Click or the Omron CP1E. They're more expensive, but have better support.

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The last reliable "cheap" PLC lines I integrated were Panasonic and Omron.  Programming was very typical for a Japanese PLC (not as sexy as Rockwell/Allen-Bradley or GE, but a rugged PLC).

https://na.industrial.panasonic.com/products/industrial-automation/factory-automation-devices/programmable-controllers

The Omron CP1 line is a single unit processor & discrete/analog I/O with add-on modules.  I believe the software was very inexpensive (~ $100).

https://www.ia.omron.com/products/family/2064/

If you want a dandy simple PLC with a HMI built in and dirt-cheap software, then Unitronics may be for you.  If your code is to be simple, and it sounds very straightforward, this could be a great solution.  It would be my pick in your situation.  

http://www.unitronics.com/plc-hmi/the-all-in-one-control-solution

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Thanks so much.

I did not even know Panasonic made a PLC  ... I suppose why not, even my camera is made by them.

I have used a lot of Omron parts with good luck.  I do see they have an analog add on module.

I do like the Unitronics unit.  I like the idea of an all in one unit.  I will give them a call on Monday to see what there prices are.

Thanks ..... Mike

 

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The Idec Smart Relay used to be a rebranded Siemens Logo, not sure if it still is, but after a quick look at both websites I would say they are still buying them from Siemens.  Haven't touched that stuff in a decade.

Panasonic bought Aromat who made micro PLCs.

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I actually used a Siemens smart relay years ago on a project.  I thought they did not have analog outputs but I see looking at there page that they do offer it.

I will have to take a look in that direction also.

I appreciate the tip!

Thanks ..... Mike

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I've used several "cheap" PLCs, including Keyence (KV300 series), Eaton (ELC series), and Siemens (LOGO series). I've recently been looking at the Automation Direct DL205, Productivity 2000 series, and CLICK series. Most of these offer low cost CPUs and very reasonably priced expansion modules. Analog I/O and ethernet modules are usually available. Programming software is available, sometimes free, sometimes for several hundred dollars. If you plan to use an HMI I would recommend the Eaton and Automation Direct products. My personal favorite is the Siemen TIA series (1200, 1500) but the programming software cost may be a factor for you (>$2000.00 USD). Another suggestion is the Codesys hardware. It is rebranded as Turck, Beckhoff, B&R, and Wago (to name a few). I'm sure there are others. I think Turck offers their programming software free. The codesys software used to be free but I don't know if it is still free or not. The hardware I/O modules are physically interchangeable between vendors (I've used Beckhoff and Wago I/O in the same rack) and are usually available at reasonable cost. This is all I can think of right off the top of my head. I'm sure a couple of weeks from now I'll think of something I should have added. I wish you well in your project. If you have any questions you would like to send to me directly, please feel free to do so.

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I've done several cheap PLC comparisons for clients and one of the best options from both pricing and capability is the Automation Direct Click. I've found it inexpensive, especially for analog I/O, and the software is free and easy to use. It won't work for an extremely large amount of I/O, but for small to medium projects it does a nice job.

Another option that I've wanted to try but haven't had the opportunity is Velocio. They're cheap, but I don't know much else about them.

On the HMI end, I simply do not like the C-More micro. Also, in a recent comparison, I found that the Mitsubishi GS2000 series beat them out on price. Mitsubishi software is not free, but it's fairly inexpensive, and I find them easy to work with.

Another less expensive HMI option that I have not yet tried are Maple Systems. I also recently heard about Kinco brand, which is a bottom dollar Chinese HMI. I wouldn't want to use it for industrial work, but it might be fine for a home project.

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Much will depend on your application requirements regarding use of an inexpensive PLC.    For your consideration, I submit the offering of Embedded Ethernet PLCs from Triangle Research.  More information can be found through our web site.  We are an authorized TriPLC distributor.

http://www.eternity-sales.com/tri-plc/tri-plc.htm

 

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Fantastic info!

I don't really need an HMI on this project .... it would be "cute" (nice to show everyone what valves are on, when the pump is running, where the elevator car is, ...) but no real need.

I want this to operate as close to a "real" elevator as possible ... with the addition of a couple of e-stop buttons ( just in case ).  There is only two floors so it is quite simple.

I have not got the I/O map completed as I am waiting of a few last items ( door openers as such ).  I am not sure what they will require.  I am "guessing" there will be about 20 digital inputs, 10 digital outputs and 1 analog output.

I am beginning to assemble all the hydraulic equipment. 

As I said, so far, all of the companies I have done work for were quite large (like Westinghouse Nuclear) and already had a plant standard ... usually money was not an issue with them.  Working on a "home" project is a lot different.  I want to make it safe and reliable but need to watch my budget.

Looks like I have a good amount of  homework .... I will look into all your suggestions.

Thanks so very much again!!!!!!!

Mike

 

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Mike,

Based on your last post, the following options are available:

1.  Fx2424 - http://www.eternity-sales.com/tri-plc/fseries.htm

This unit would provide you with all your I/O, including analog.

2. FMD1616-10 - http://www.eternity-sales.com/tri-plc/fmdseries.htm

Should you require the full 20 inputs, you would require an expansion board (information available through the same link).  If you will only need 16 inputs, you will be able to do so with a single board.  Analog is included.

 

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Wow, I didn't think anything from Allen-Bradley was free!

I have been working on the mechanics of my elevator.  I am actually doing some welding today and have had to learn to bend pipe (1/2" seamless stainless for the hydraulics).  I am quicker at electrical work than mechanical so like all my projects, it is taking longer than expected.

I will be getting back on the electronics next week. 

Thanks for all the advice everyone!  I will look into all these options!

Mike

 

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Awesome!  I will look this up.  I actually got the elevator working with manual controls a couple months ago.  My wife saw the upstairs of her house for the first time!  It is rough but good enough for the summer.  I am trying to get the shell of the workshop up right now and will get the elevator finished this fall when the weather changes.

Thanks again ..... Mike

 

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