Micro PLC with isolated digital inputs 1

[analogkid2digitalman]

Does anyone know off-hand of any micro PLC's with isolated digital inputs?

Requirements are minimal:
4 discrete isolated digital inputs (logic high at TTL to 24VDC levels).
4 outputs, common can be shared, relay or sink/source for 24VDC 150mA loads.
Minimal non-volatile memory, I am guessing about a dozen rungs of pure boolean logic.
Universal AC or 24VDC powered.

I do have a non COTS solution hashed out, but a COTS implemetation would be nice and quicker (need to deploy to 5 laser CNC systems) to implement.
Another option is to add isolators to a PLC that shared a common input.
Prefer isolation since the control signals needed to set the state of a green/yellow/red safety beacon are coming from various controllers, lasers and a PC I/O card.
The controllers are powered by floating supplies that I'd rather not start tying up to common grounds.

Thanks

-AK2DM

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"It's the questions that drive us"
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[analogkid2digitalman]

Forgot to mention, I did come by Galil's Pocket RIO-47xxx series, but it does seem a bit of overkill:

http://www.galilmc.com/products/rio-47xxx.php

-AK2DM

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"It's the questions that drive us"
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[itsmoked]

You should have put this in the PLC forum but here's my take on it.

Hi analogkid2digitalman. Sorry for the delay I couldn't reach ET all day yesterday. Some network bollix I guess.

Most all PLCs have isolated inputs and outputs - but - isolated in groups.

I'm now a big fan of the Click Series from Automation Direct. They're very inexpensive but still provide a lot of proformance for the cost. You can get a CPU and then an 8 or 16ch IN and an 8 or 16ch OUT and use each block of four inputs and outputs completely isolated from the rest. Just bring over the sources or returns from your various machines to reference the various four block channels. Some of the CPUs have two 4 bit blocks already so could achive 4 isoltaed channels by adding only 8 channel I/O modules.

http://www.automationdirect.com/adc...ers/CLICK_Series_PLCs_(Stackable_Micro_Brick)

Another consideration is that you mentioned 150mA. I don't know of a lot of PLCs that can source or switch that much current. Relay based models can if your cycle time is not often.

The software for the Click is excellent and free. You can get it there.

You mention non-volitile memory. It would sure be better if you could skip that ball and chain. It adds an unwanted battery in a production/industrial environment and probably about $25 to CPU prices.

Also you metioned light masts. One thing I've done is skipped the masts and just used the C-MORE 3 inch monochrome white HMI touch panels. In alarm mode they can be made to flash a brillant [!]RED[/!] Then because it's a display you can actually communicate with the user to explain what the error is and allow them to push all sorts of soft buttons with the panel to acknolledge the alarms or silence them or whatever without a bunch of additional mechanical switches. Just a thought.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[analogkid2digitalman]

Keith:

I did not even realize there was a PLC forum, I don't venture much out of my fishbowl of Threadminders very often.

I did check out the Click and the Direct Logic series, very nice. I think I'll go with a Click and add quad pack opto module prior to its inputs.

A lot of the other brands I checks out had NPN/PNP's that had drives in the range of .3-.4 Amps. I changed the model of light tower, the new one is LED and is only 75mA so the Click outputs will work.

I was under the assumption (old school) that the battery was needed for program retention in memory but nowdays it looks like EEPROM is used and the battery is used to store variables. I have no need for variables so I should be good to go.

The light tower needs to have 360 degree visibility in this case, but thanks for the tip on the HMI usage.

I'll download and go through the manuals for the Click just to make sure I am good to go. Free software is a bonus.

Thanks for the feedback Ketith, much appreciated!

-AK2DM

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"It's the questions that drive us"
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[OperaHouse]

With this few I/O it seems like a good match for the UNO. While the output is easily taken care of by a couple buck ULN2003 output board, I couldn't find a COTS olution for opto inputs. OPTO22 modules would work for a COTS solution and these are cheap but the mounting board will cost as much as everything else. Did find this interesting solution and it looks like you can use all the Arduino UNO software with it.

http://www.ebay.com/itm/KMTronic-WE...841?pt=LH_DefaultDomain_0&hash=item416fbe2639

 

[itsmoked]

Pretty cool board there Opera.

A2Dman drop me a line if you have any Click questions.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[analogkid2digitalman]

Operahouse:

I was toying with that idea too! Over the holidays I was playing with my son's new Christmas gift I bought "him". There are quite a few expansion bricks and I/O add-on's for the Arduino out there. Pretty neat, maybe next I'll get a Raspberry Pi to learn Linux and see what it can do.

Keith:

Currently writing up a req for the C0-00DD1-D Click along with an expansion 8 point 3.3-5VDC input module. After reading the manuals, I see your point about the I/O group commons isolation. No front-end isolation needed now. I will also get the 1.3A supply to be on the safe side and also use it to power the lamps.

It should be a nice self-contained solution with minimal wiring.

Thanks again, gentlemen.

-AK2DM

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"It's the questions that drive us"
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[OperaHouse]

It wasn't till I posted that and was checking the link that I noticed the board was from BULGARIA! The UNO is easy and cheap. I figure it is only a matter of time before there are lots of one board solutions. I did a store animation project using a serial I/O board like the OPTO22 Majic. This guy happens to be a friend of mine and his crazy grocery store was included in a History Chanel Modern Marvels episode. This is made from old DC-8 parts.

 

[itsmoked]

Powered with hot sauce no less..

Keith Cress
kcress -

http://www.flaminsystems.com

 

[analogkid2digitalman]

Keith:

My Click came in today, wired it up and I entered the demo in the manual. Up and running in an hour!

The programming software is pretty good, my how things have changed since the mid-80's in the A-B, Gould, and Modicon era at General Motors when I last worked with PLC's!

(Terminals and tape drives)

Thanks

-AK2DM

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"It's the questions that drive us"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 

[itsmoked]

A new baby brought into existence in just an hour! Congrats.

Here's my last Click project. Notice all the blinky lights on the Click.

https://www.box.com/shared/static/8j85a2gp8o52foh1pljg.wmv

Keith Cress
kcress -

http://www.flaminsystems.com