Beginner question: PLC suitable for this project?

[Ozone77]

Well if the device fails and the outputs are all open there is no problem. If the device fails and leaves any of the outputs closed there might be a problem, this would be an issue no matter what sort of system we use.

Regarding cheaper micro options, we made our first prototype with a BASIC stamp chip and currently use another simple microcontroller but the total cost of manufacturing a unit from a seperate components (controller chip, custom pcb design, relays, power supply, box, connectors etc) in the small quantities we require is what leads me to looking at pre-packaged solutions with all these built in.

 

[Doug_Adam]

As a comparison,
A Siemens Logo (programmable Relay) with 8 inputs and 4 outputs costs around $350 for a starter kit and $250 per relay. A starter kit has programming software and cable as well as one relay.
Even RS electronics doesn't mark them up too much, so you could get out the catalogue and look up "PLCs and Programmable Relays" under the Process Control Section.
You could also visit NHP, which has a show room in Melbourne. They generally have a few items set up for testing.

 

[markhommer]

You could also consider a CB220 microcontroller from Cubloc, as an alternative to the Parallax microcontroller. The Cubloc can be programmed in Basic and/or Ladder Logic and the programming software is free.


http://cubloc.com/product/01_01.php?PHPSESSID=4d8da414bc92a90ea83ef10b070d1b32

Regards,
Mark.

 

[yfcarer]

yeah ,any PLC can suffice ur request...so choose a cheap one..good luck!
by the way,yfcarer,r u from tianjin?nice to meet u

Hi, friend!
Yes, I am from Tianjin China.
And are you from AnHui?

 

[Stephen Luft]

Owen,

If you are looking to keep the look of your product consistent with what you are currently using, we offer a board level / embedded PLC product, that offers the appearance of a custom designed board, while being off the shelf.

We do have a distributor in New Zealand. If interested, I can forward you their information.

If you are interested, you can click on the link

The PLC offers it's own internal timers, that would operate separate from your PC, therefore giving you the required independent control required for your outputs.

If you have any questions, feel free to contact me through the forum or email at the bottom of the post.

Please note that I am employed by Entertron Industries.

Hope this helps.

God Bless,

 

[Ozone77]

Thank you all for the help and advice. I've now got lots of options to research, much appreciated.