Emulate PLC software on a PC?

Hello:
I would like to practice programming but I don't have a PLC. Do you have any suggestions?
Can anyone tell me if there is a PC software program that can emulate PLC software? If there is, were can I get it?

Thank you.
Warm regards,
Newbie

Try www.thelearningpit.com

They have a program called logixPro that you can download and try for free. It simulates Allen Bradley's RSLogix.

Do you have any "Computer Programming" experience? Do you have a "C", "C++", "VB" or "VB++" Compiler?

If YES to both questions, then you can build your own PLC.

To get the REAL effect, in fact, to produce REAL PLC-type control, you would need to get an "Input" card and an "Output" card.

(If you are a real bit-wienie, you could use your parallel port. Search the NET for Jan Axelson & Parallel Ports)

The key to the design is to mimic the operation of a PLC. That is, Read the inputs, Eval the ladder, then Write the outputs. Then repeat the whole process (on a periodic basis). The fast your processor, the shorter your "scan-time". Although, you have to be aware of the speeds associated with your Input card.

I don't know of any typical PLC that has a 1-Gig processor. That is a typical speed for todays PC's. Timing Critical Applications??? Is a PLC REALLY the right answer???

Your program won't operate exactly like a PLC. That is, the nature of a PLC program is that its primary mission is to automatically loop in the manner described above -- more or less like a GO-TO.

GENERALLY, the shorter the code, the sooner the PLC can GO-TO and restart the process. There is a certain minimum amount of time dedicated to house-cleaning. So you can't really approach Zero-Scan-Time.

On the PC, the PLC Program is DEFINED as a SYSTEM INTERRUPT ROUTINE. That Routine is "CALLED" by a particular SYSTEM INTERRUPT (This is definable). The System Interrupt is specified to occur on a time-basis (just like other normal, PC-type, timed Processor Interrupts).

When the Interrupt occurs, the Interrupt is handled by the processor on a right-now basis. After a small amount of house-cleaning, in preparation for handling the "Interrupt Routine", the Interrupt "CALLS" the particular Interrupt Routine.

That Interrupt Routine IS the PLC Program!

The PLC Program runs to completion and then goes back into hibernation until the next time it is "Called".

And, so it goes...

It's really not such a spooky thing, if you have the tools and the in-sight!

Goinkey,

We offer a PLC programming software package, Eware32, that includes a run simulator. You can download it from our web site directly.

Our simulator allows you to test/run a developed program in software, without the PLC. You can view the results of your program
in two forms of monitoring - ladder flow and table. This feature is included with our ladder logic programming software.

www.entertron.com

Once you have downloaded our software, in order to unlock it, you will require a password. In order to obtain the password, you will have to complete our product recommendation form or customer contact form. There is no charge for this, the software is free.

Hope this will help you.

God bless,

Stephen Luft

Goinkey,
I was able to get a demo unit from Moeller, which included a plc,power supply, touchscreen, all software, cabling, etc. My sales rep just dropped this stuff off for me to use for three months or so, to see if I like it!!
Not only do I get to mess around with a new gear and programmiing language,(all my experience is with A-B), but I have access to their support and advice, as well as this forum.
If you could work something out like this, there's nothing to lose.
good luck,
Chris

I want to refrain from starting a PLC versus PC based control thread, but....... Terry, what would you recommend using if using a PLC wasn't an option (hypothetical question, I know)?.. And I guess you could be witty and answer "PC based control, of course". But I am interested in your honest opinion.

The first answer that pops into my head is... "Commodore-64" running a Basic program. That's not exactly a "PC" - at least, not in todays' sense of "PC".

A lot of folks just don't know how great a tool that thing was. I've always regretted selling mine.

Since you specify PLC's not being an option (not available? non-existent?), and you seem to be calling for a non-PC answer, I'm not fooling when I suggest the Commodore.

Basically, my anwer is, I would use a Micro-Processor based controller. There are several options available. I need to have smarts and speed in there. Maybe, Roll-yer-Own? Ultimately, a Processor is a Processor is a Processor! The smarter and faster, the better.

I wrote a whole lot more... it was too large! The site choked on it and puked it back.

This will be enough of an answer for now... ya think?

Given that one has a PC and doesn't want to program PLCs

I would look at:

z-world Rabbit Fast floating point.
TI MSP430 Very low power. Great for battery applications.
Atmel AVR Nice instruction set. Easy to learn. Small foot print

We have bought one or more development/trainer kits from each of the above. I have bought 2 Z-world systems for employes to play with.
We are doing a project now for the BPA that is using the TI MSP430.
We have also bought some DSP evaluation kits. Many of these kits cost less than 100 US$

We buy many different evaulation system just to get the feel of the cpu. When the engineers get bored with the evaluation kits they becomes toys or part of test equipment.

Hi goinkey

Check the Square D web site and search for the Zelio software written for their brand of a smart relay.
This isn't true PLC software because it is limited to inputs, outputs, memory bits and a limited number of timers and counters with a bit of text mixed in (for the models with a display). But it will get you going with the basics and once you have completed writing your program it has an excellent simulator.

www.squared.com

Toys?

How about a Lego Mindstorms ?

They've got an "RCX™" block that has 3 discrete inputs / 2 discrete outputs. Create and download a program.

Is it a toy, or a small PLC?

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To misquote Voltaire: "If PLCs did not exist, it would be necessary to invent them".

I agree with thelearningpit.com The software is called logicpro and is free for 30 days. Then if you like it, it cost less than $30 full the full program. Ir comes complete with simulations...