PLC comparisons

Hi.
I have a fairly simple PLC application and I must now choose a PLC. I have looked at the Omron ZEN and the Moeller Easy 412 & 619. My application is:


Based on the absence of 115VAC on the PLC input terminal, I will have to try resetting a 115VAC ultraviolet light (ballast load) X times over Y minutes. If after successive power resets, there is still no 115VAC on the PLC input terminal, I will have to provide 115VAC to a control valve for Z minutes, and, after some specified time, repeat the cycle. I will require retentive counters to know how many retries, etc.


How does the ZEN compare with the Moeller Easy series? Are there other inexpensive PLC's out there that could handle this? I have tried the Moeller software demo and it appears to be fairly easy to program the Easy PLC's.


Thanks,

MG.....

Hmmmm... The "Zen". Hadn't heard of that one yet. I guess Omron decided to jump on the bandwagon with their own programmable relay. Now, who's gonna start brand labeling THIS one?...

I had a quick look at the Zen and it seems to be basically the same as the rest of the programmable relays. Notice the term 'programmable relay'. These are NOT PLCs, though the programming is similar.

Your application is simple enough to be done with any of these units, so it will probably just boil down to which one can you get the cheapest...

Here's a few others to check out (clickable links)...

Telemecanique (Schneider Electric) "Zelio"
Allen Bradley "Pico"
Siemens "Logo!"

beerchug

-Eric

Generally, I don't understand why you use lighting voltage for process control I/O.

If you have some model of PLC in your plant, use that. This is spare part question also, even your process is 'small' in this case.
Will you need new software developper and it's upgrades in the future etc..

I have been using the ZEN and ZELIO for some time. The big difference is that the ZEN is EXPANDABLE. Sometimes do not have to buy a larger and more expensive PLC.
beerchug

What's your budget, what country are you in, what does your plant use, what can your local supplier source?

As for Omron I wouldn't go near them, have you thought of the Twido by Schnieder??? More powerful than equivalent AB or Siemens offerings, however for ease of programming you can't beat the Micrologix by AB, a child could program this.

As for Omron I wouldn't go near them

Click to expand...

Why?
Twido is OK. Software is a bit fiddly. Using them on some small jobs as they fill a hole in the market place.
beerchug

I'm going to put in a plug for my favorite small PLC, the AutomationDirect.com DL-05. The PLC and software are both inexpensive, and the software is very easy to use. Any extra hardware cost will be offset by the shorter learning curve and programming time. www.automationdirect.com

Have you checked Siemens? They have an inexpensive, programmable timer that will do everything you mention & then some. Plus it's networkable if you desire that in the future.