Please suggest a suitable cheap PLC for this application

Hi,

Is there any cheap PLC (less than 100 USD) that has 4 digital inputs/outputs (not relays), RS 485 communication, ethernet port (if possible) and software for programming ??

something like these look OK.
http://www.automationdirect.com/adc...Series_PLCs_(Stackable_Micro_Brick)/PLC_Units

the digital I/O module is given below.
http://www.automationdirect.com/adc..._Series_PLCs_(Stackable_Micro_Brick)/DC_I-z-O

The project I am working on is a motion control system for controlling a stepper motor and using limit switch inputs.

Are there any other such PLCs ???

Are rockwell products expensive compared to the one above, what about the Pico series ??

thanks
a

http://www.automationdirect.com/adc/Overview/Catalog/Programmable_Controllers/Do-more_Series_PLCs_(Micro_Modular_-a-_Stackable)

Instead of the Click from Automation Direct, I would go with the Do-More PLC from Automation Direct. It can come with a built in ethernet port and the programming c/w simulation is provided free.

Regards,
Garry
http://www.accautomation.ca

arbj said:

...(less than 100 USD)...

Click to expand...

Only on eBay.

Cheap comes out expensive. The way that I would look at is, what’s the application worth I.E. how much money am I willing to spend to get the benefit of whatever it is I’m trying to do. The reason I take this approach is sometimes (a lot of times) I see people spending way more than they would have normally spent had they done it right in the first place. One of the (many) tasks I have at work is tech support and I can’t tell you the number of times someone is in trouble because they tried to do something on the cheap and it simply won’t work. It’s not to say that you can’t do thing with “cheap” PLC’s but keep in mind that for the most part it is a “you get what you pay for” industrial automation world and if the task at hand is important and/or complicated as I said before you need to evaluate what the application is worth and budget accordingly. You might save a few bucks now but you could also find yourself down the road regretting what’s been done.

With an I/O count that low, there are many stepper motors that have a built-in controller that you might be able to use.

The Schneider MDrive Plus series and the JVL QuickStep come to mind as examples of this type of integrated controller/motor.

Instead of the Click from Automation Direct, I would go with the Do-More PLC from Automation Direct. It can come with a built in ethernet port and the programming c/w simulation is provided free.

Click to expand...

But its more expensive than the click PLC. My application needs only a RS485/RS232 port (apart from programming port).

How is the click series PLC quality and reliability ?? Are they prone to failure ?? I know this depends on many things and that even good ones can fail, but in general how reliable are they ??

I am bit worried about the 100USD price, as it looks a bit cheap for a supposedly high quality product.

thanks
a

I was thinking of using it in our main stream products, so

I've been using them for years. They work fine. No failures.
Maximum 8 modules.

Thanks kethkyll,

unfortunately the CLICK may be unsuitable for my application as I need to generate stream of pulses for a stepper motor controller, as the pulses have to be quite fast (21 microsec high time, 2 microsec low times), but this PLC looks appropriate
instead..http://www.automationdirect.com/adc/...nits/D0-05DD-D, but unfortunately this does not have RS 485.

thanks
a

arbj said:

but this PLC looks appropriate
instead..http://www.automationdirect.com/adc/...nits/D0-05DD-D, but unfortunately this does not have RS 485.

Click to expand...

Your link does not work but I think you are pointing to this one

http://www.automationdirect.com/adc...ogic_05_(Micro_Brick_PLC)/PLC_Units/D0-05DD-D

What RS485 are you looking for they (the Click and D0-05) both have the same ports, also the D0-05 has one spare slot and you can add a Ethernet port, also the D0-05 has two ports

See here http://www.automationdirect.com/static/specs/d005ddd.pdf and http://www.automationdirect.com/static/manuals/d0user/d0user.html

The least expensive PLC I know of that can do this is the Eaton ELC. There will be a bit of a learning curve with the pogramming but it is capable and inexpensive.

<disclaimer - I work for a distributor that sells Eaton electrical products>

Someone here used to have (maybe still has) the signature "Quick. Fast, Cheap. Pick any two". This is always true.

ndzied1 said:

Someone here used to have (maybe still has) the signature "Quick. Fast, Cheap. Pick any two". This is always true.

Click to expand...

I think it is: "Good, Fast, Cheap"

Ha, that's what I get for posting from my phone in a quick spare moment.

You are correct! Good, Fast, Cheap.

Dl05

arbj said:

Thanks kethkyll,

unfortunately the CLICK may be unsuitable for my application as I need to generate stream of pulses for a stepper motor controller, as the pulses have to be quite fast (21 microsec high time, 2 microsec low times), but this PLC looks appropriate
instead..http://www.automationdirect.com/adc/...nits/D0-05DD-D, but unfortunately this does not have RS 485.

thanks
a

Click to expand...

The dl05 is the way to go, it has stepper outputs.

I haven't had a chance to try one of these yet but they look quite interesting: http://velocio.net/
And inexpensive as well.

Ken Roach said:

With an I/O count that low, there are many stepper motors that have a built-in controller that you might be able to use.

The Schneider MDrive Plus series and the JVL QuickStep come to mind as examples of this type of integrated controller/motor.

Click to expand...

I had some interesting experiences with the MDrive where the motor would go in the wrong direction occasionally. This was on the models that had their questionable integrated controller. I've also had a couple drive stages go bad. I don';t use them anymore. The JVL stuff is fairly decent from what I've heard though.