Small PLC choice?

[fsck]

I need to choose and deploy a simple PLC. It will have about 10 digital inputs and 10 digital outputs, split between two specific locations. The main & remote locations will be connected by 100baseT and RS-232, carried by some fiber converters we're using.

It would be nice to also be able to observe status/state via a PC application.

We might want some analog inputs for monitoring, too.

It sounds like some ilk of Automation Direct ClickPLC might be what I need. I've been reading their The Fine Manuals. They look almost too good a fix: inexpensive, expandable, etc.

Comment?

One thing I don't see is a module for monitoring RMS AC voltages. Does such exist, or does someone want to share a recommendation for a AC TrueRMS-> DC converter?

Another issue is remoting of half the I/O's. I've not found any discussion on any other hardware I need, such as a RS-232<->module adapter. And what happens when the link fails? Dp the outputs all revert to off or?

Is there a good forum for ClickPLC's to join?

 

[danw2]

Some specialty power recorders (orders of magnitude more expensive than the Automation Direct) can take AC directly, but it is most common to use a transducer which outputs a common low level DC signal like 4-20mA or 0-5Vdc for AC volts or amps. Then the PLC has to have a corresponding analog input.

Typical example:

http://www.phoenixcontact.com/signal-level-matching/31244_14926.htm

 

[fsck]

Thanks but it looks like the ClickPLC is a dead end. There's no good way to have remote I/O. I can put a 2nd CPU at the other location, but the comms between them is convoluted, I'm told.

So I must reopen my PLC search.... Grrr.


(And one, much less 3, of the above would cost more than everything else in the subsystem. I can use a

http://www.egauge.net/

and grab the values from there.)

 

[robertjo24]

We use the Automation Direct DL-405 PLCs and they work fine for smaller implementations. And, they are cheap enough to have many spared on hand.
If you need to remote IO, you can link two PLC's (they are relatively cheap) via RS-232/485/422 and have one pass registers to the other.

 

[fsck]

I'll go read up on the DL-405; I infer this is not a Click-PLC, however?

The RS-232 is easy. It's what I was told re: comms programming that bothered me.

Hmm, the -405 TFM makes mention of a DC-powered DL-440, a real plus. Lots of pictures of communications at the beginning. I find DirectNET mentioned but infer it is run over 232/485. I'll have RS232 tunneled over fiber so that should be OK.

It's clear this a far more complex product, however.

Thanks for the starting point.

 

[catserveng]

http://www.flex-core.com

makes a number of of good quality AC voltage, current and power transducers, Ohio Semitronics is another source.

 

[fsck]

Thanks, but I'm astonished at an electronics firm with nothing but a printed catalog!

 

[djs]

An A-B Micrologix 1100 PLC costs around $500 and has a builtin ethernet port.

 

[fsck]

I like Ethernet! I'm off to read up on it.

(While the DL-440 looks like it would work, it's ~10X the price of the ClickPLC and far more complex than I want or need.)

It's clear the AC measuring is a luxury best met other ways; I can use phase monitors such as the

http://www.icmcontrols.com/products/product.php?prod_pk=50

to tell the PLC when Reddy Kilowatt is loafing.

 

[fsck]

I've learned enough already that I should restate my requirements:

a) Small PLC, i.e. inexpensive.

b) Remoted I/O as well as ones at CPU, <10 I's & O's at each.

c) DC Powered [It's controlling a backup power system, so...]

d) No large one-time costs [i.e. programming sw license, etc]

e) Analog inputs might be nice but no dealbreaker.

 

[jraef]

Siemens' new S7-1200 is about as inexpensive as you can get right now. "Remote I/O" per se is still a ways off, but the smallest CPU with built-in I/O (6DI 4DO) is only $177, so it's usually cheaper than a lot of remote I/O scanner cards alone. All you would do is connect both CPUs via Ethernet and one can see the I/O of the other, so it might as well be remote I/O. They have 2 AI on board, you can add Analog cards if necessary. They all have built-in Ethernet for communications and programming, you can add a serial port if you have to have it. They are all available 24VDC. Software includes the ability to program their new basic HMIs as well. It's not free, but cheap and if you buy what they call a "Starter Kit" it's damned near close to free, no licensing fees etc. either.

Disclaimer: I used to work for Siemens so I suppose I am still a little biased, but technically they no longer pay me to care. I just really liked this product when they released it, I am using it on a large project right now, it's pretty sweet.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[fsck]

Siemens' new S7-1200 is about as inexpensive as you can get right now.

Sounds interesting

Rant: They could learn from A-D about usability of web pages. I'm in a maze of twisty little web pages, all alike. XYZZY was no help at all.

I'm seeking the basic stuph; what you need to get started, etc. I find everything but.

[Can you guess the WX here turned hot and cranky again?]

 

[jraef]

To navigate Siemens' web sites you have to train yourself to think like a German, i.e. you are expected to know where it is in the first place, because everyone knows, jawohl? It also helps if you know someone...

S7-1200


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[xJAyx]

You might consider WAGO 750 series PLCs. They have plenty of communication options and their IO is very inexpensive and dense to save on panel space. Bonus for you: They have a 3 phase power monitpring module. You can install a remote IO rack within 5 meters that is a simple continuation of the PLC rack, so much so that the master PLC does not even know it is an extension. You could also add another rack with a coupler, or another stand alone PLC using Modbus TCP on your PLC, or add a communications module.

They have a webserver that you can build a remote acees application for.
They are 24VDC powered.

As long as the cost is inline, this could be your best bet.

 

[fsck]

It is hard to not sound unappreciative... but please try & include specific links to the most general of background pages on recommendations. Or terms to find same.

Google is not yet able to read minds as to my needs/intent. I waded through a dozen links on the S7-1200 trying to find one NOT starting off as I if I already knew everything about it. I finally found the "S7 1200 Easy Book" which is easier than others but....

Thus far, all the WAGO 750 links I find are for some small part of the puzzle; such as the terminal blocks. The magic that tells me what the castle will look like once I build it still eludes me.

No wonder so many speak so well of Automation Direct; you can grok what they are selling....

 

[Skogsgurra]

fsck

Try googling WAGO 750 as indicated by xJAyx. It brings up lots of stuff on the WAGO system. Qualify with PLC to refine search.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[JADeak]

Also look at Sixnet (

http://www.sixnetio.com).

They have RTUs and controllers and remote I/O modules.

 

[xJAyx]

http://www.wago.us/products/337.htm

http://www.wago.com/wagoweb/documentation/index_e.htm

 

[pocketooth]

check

http://www.tekitech.com

(fatek usa)

FBs-20MA + FBs-CBE.

ladder programming Software is free. To view PLC data from PC, download the Facon communication server (free) via ocx or DDE. (

http://www.fatek.com)

Power option can be DC24 or DC12(default 110/220 AC power) at same price.

I usually use multiple Fatek PLCs communicate with each other via Ethernet (very long distance). This is a better remote I/O form when PLC is not too expansive.

Analog input module are available as well.