Ladder Logic

Do you define "good" as being free? Or should "good" be manifested by ability?

Do you expect to be paid for your efforts? So... why should the maker of the sort of software tool you are looking for not expect to get paid as well.

Buy one!

Mitsubishi provide a version of GX Developer that is free for their low end range of PLCs you can produce LAD schematics and print to varying degrees of complexity. Siemens also do a version of Step 7 (Lite) which is free to download off their web site. Haven't really used it so can't comment on its merits

Pen. paper, a ruler, a lettering guide and a steady hand.

After that you pay. Autocad works well.

TRY tucows.com

My God! Ladder logic?! Are there any FORTH programmers out there, too?!

If you want to type in ANDs and ORs and NORs, then have it turn to a LL schematic, I don't know. You might check Telemechanique for a programming environment. They're big into PLCs and such.

If you just want a good program for creating LL drawings, try Adobe Illustrator or Visio. Just drag out some lines, use the space tool to make them even, then draw one of each of your circuit components. From there, it's just a matter of Cut-n-paste.

I think GW has it right.

www.tri-plc.com/trilogi.htm

Here is the program you are looking for.

Great Free Site Great Info.YES GREEDY people want to make a lot of Green.

As a person being a long time in the ham radio world we have learned to get things for FREE.

We also give back many times over "FOR FREE"

Thanks to ALL THAT WANT THE FREE way.

Keep up the Good Job.

I have not tried this package, but it's free. I got the link from CR4 some time ago.

http://tinycad.sourceforge.net/index.html

There is a free online simulator based on the Allen Bradley PLCs/SLCs here that features drag and drop rung building. See : http://www.plcsimulator.net/

If I'm correct, I thought Ladder Logic was an indulgence for all those guys that used to program using virtual solenoids because that was what they were used to. I thought all those guys had died by now...

Nope, just a dying breed!

I repair/renovate old school machine tools. Nothing "plug & play" about what I do. Pencil & paper work well but, why not utilize these new tools?

Thanks for the information. I will try some out today.∞

Im refused to use an PLC for (example) only one pump, one tank and two switch level sensor. Only need one rele and ladder logic. Why overwork and not offer and cheap possibility in some cases ?

Check out Rockwell's (AB) Control Logix platform...Newest default offering is ladder programming. You have to buy the add ons for stuctured text and function block or buy the expensive all inclusive software from the beginning.

Now, AB uses ladders where function block or structured text make far more sense. The old Reliance Automax was extremely powerful and in many cases had more programming flexibility than the CRLX. The CRLX however is far more powerful for making online changes for both programs and configuration. The utilization of RSlinx makes communication flexible, but in my opinion it is poorly integrated into the CRLX product.

Between the above comment and your previous one I must assume that you are not a professional and have little experience in the real world.

I do control system design professionally and find for all of the library and custom function block advantages to the IEC programming flavors , most of the implementations lack good design especially in the de-bug phase. I don't know about others but not being perfect or a sophisticated "eur-a-pee'n" I prefer to be able to correct my little foo-paws and typo's with speed and accuracy. Further the ability of my customers to deal with the lack of documentation and library source code is frustrating to them.

not o mention the some times very slow (comparatively) execution time of the programs , particularly with heavily embedded function blocks , subroutines can be extremely limiting and require more powerful CPU's and considerably greater memory space (can you say MS fat-ware?).

Personally I believe that ALL of the IEC gear is !@#$%^&*( , It costs less , craps out sooner , non reparable and can be used to add to the pollution in our world -- it just plain throw away-- and should be thrown.

IDULGENCE---REALLY?

Jon

Ladder Logic is alive and well. There are tens of thousands of Industral PLC's in use around the USA. Most of them maintained by the electricans and technicians that learned to use ladder logic in school. Almost no one in the US uses the IEC logic or statement list to program as they are just too difficult for our technicans to maintain.

Regards Mike

Bingo! IMO, Ladder Logic is still the fastest method of developing, debugging, commissioning and conveying design intent to the maintenance staff. I've written machine control logic in all of the different IEC language flavors (LL, SCL, STL, SFC, etc) but I get the fewest phone calls from customers with the ladder logic implementation because their maintenance people can quickly understand the programming and fix any problems. And that is my real goal as a controls engineer; to get as few phone calls as possible.

Yes, I have to admit that I've messed around with it on Telemechanique PLC. Also, while they may still be using ladder-logic, there's a younger bread of industrial control programmers out there. What do they use? FORTH.

It's interesting how many times FORTH pops up from underneath the hood of things. As hardcore as most C programmers are, they never have a clue that the entire operating system in a Sun UNIX box (or MAC) sits quietly on top of FORTH.

^{Shhhhhhh! It's a secret!}

I used FORTH with small embedded processors many years ago and am familiar with its tight threaded code it creates but I have a hard time believing your statement. Mostly because I've seen little support in cross-compiler/debugger support. (I say compiler but Forth is a interpretive language). Forth's kernel is small enough to be embedded in a processor's ROM but its only one step up from assembly; not the environment that is easy to debug. Out of curiosity, do you have links to support your claim.

FORTH is both an interpretive AND a compiled language. That's what makes it so easy to debug.

Go to any SPARCstation, and do a shutdown. You'll eventually see an almost blank screen. At the bottom there's like three options: c - for continue, n - new kernel, and r - for reboot (I think!). if you press n, you'll suddenly see "OK" appears on the screen. Guess what? that's the FORTH prompt! Try typing in..

OK words <Cr>

You should get a listing of all the words currently compiled. Also, you can create new words and execute them. I used to do this in boring presentations where we all had SPARCstation. People would freak to see what was running on my screen!!! Also, a friend of mine who's a tech writer showed me a SUN manual she had written years ago that showed how to change all the prompts on a SPARCstation by getting into the FORTH environment.

To get into a Mac's FORTH kernel is a little more complicated. The only time I've seen it exposed and played with it was when the hard drive crashed.

I also know several people in the robotics and medical machine business. Their stuff is all programed in FORTH. The main problem with FORTH was that it never supported floating-point math. However, like ladder-logic, It finds use in a lot of places where one never really has use for floating-point. Robots, Machines, etc...

By the way, do you know that FORTH allows you to run a program that can drop into interpretive mode, pick up new code, and compile it into the program you're running? The new code can also be generated on the fly by the program your running!

Freaky, huh!

IDEC's WindLGC and WindLDR have at least a 30 day trial of their software. If you a simple control box (some relays, timers, analog control, ins, outs, etc), and don't feel like spending hundreds, look at their SmartRelay. The starter kit is under $200 and it works well.

Go to: http://www.ab.com/programmablecontrol/plc/pico/picosoft.html and download version 6.1. Link is in the upper righthand corner of the webpage. It offers simple programming and has a simulation. It also cross-references I/O and outputs to rung.

I use it pretty much every day.