PLC Language question.

Hi All.
I have a newbie question regarding what language I should use to complete a task.
I want to us an Omron PLC (CP1L series) to control the speed of a hybrid stepper motor via its control unit, which there are many manufacturers around selling these things, which has a frequency input that translates to an output rotational speed. As I have very little PLC programming experience I wanted to know what type of PLC language should I use to carry out tasks like this one and similar.
I’ve been going through the documents for the unit and have put together a couple of simple ladder programs so far. The list of languages is listed below, and it’s a bit confusing as to which one fits the bill.
Any help in narrowing down on what I should be concentrating on would be appreciated.

Ladder Logic.

Mnemonic Instruction.

Sequential Function Charts (SFC).

Structured Text (ST).

Function Block Diagram (FBD).

Thanks
Martin.

Since you are just starting out, I think you will find that Ladder Logic is the easiest to work with. You should have no problem doing the application in ladder format. Also others going behind you are more likely to appreciate that choice. Keep it simple and document everything.

ok, thanks, what about ST?

ST is the easiest one for this task, you can use while and fornext loops.
i have to warn you as the maximum speed is limited by the scantime of the PLC.

I would use ladder. Look up (3-20 High-speed Counter/Pulse Output Instructions) in the programming manual of the PLC.
http://industrial.omron.com.br/uploads/arquivos/CP1L%28H%29_2007_W451-E1-03_PROGRAMACAO.pdf
In my opinion it does not matter what language, as long as it is well documented. This way going back years latter to look at the program will be easier.
Regards,
Garry
http://www.accautomation.ca

Definately ladder. I only use ST for complex maths - have too many customers thousands of ks away and trying to sort through ST on the phone with a sparky who has limited knowledge is impossible. They can understand ladder with a bit of help.

Thanks, all for your comments.

A question for shooter, you said that the maximum speed is limited by the scan time of the PLC. Isn't this true for all language types used in a PLC?

Martin.

yes sure, and the IL is in most cases the fastest after copiling, as these instructions look the most to the copiled language.
ladder is one of the slowest, but you will not notice it, unless you have really big programs.
I mean, that a PLC is not the best for fast processes, or you need an arduino, or a special card the freq you can make is about 50 Hz to be steady anything above will not be a steady signal, as the loop of the plc is taking time to get all inputs, and set outputs, and communication, etc.

Most PLC's, even the low end bricks have built in pulse generators or have I/O Pulse cards available and can produce pulse streams that I have seen ranging from 5kHZ to 25kHz. More than fast enough to do simple motion with an indexer/Stepper. These are done in hardware and not dependent on scan time for the execution of the pulse train, only the initiation.

I agree with ATU. The pulse outputs are done independent of the PLC scan. Scan is all relative. It generally does not make a difference if the scan is 2.5 msec vs 2 msec.
http://accautomation.ca/who-else-wants-to-know-how-a-plc-scans/

Regards,
Garry
http://www.accautomation.ca

ATU is correct, the one I have personally worked with is the CTRIO for the DL06 depending on wiring its top was 200k or 500k. Depending on which model of the CTRIO you buy it has built in configurable motion control models, and multiple control methods.The scan time only effects how fast the PLC can react to a change in motion.

For motion control I do suggest sub routines so you are never scanning unnecessary code.

By the way I am not promoting this setup, just using it as an example of what is out there.

One word of caution when selecting a programing style. Who is going to work it / troubleshoot? I would pick the style that is easiest for the plant guys to work with, unless you want to be the guy on call 24/7.

Definitely ladder!!
I've done about a dozen CP1L & CP1H programs to control stepper motors, every one of them in ladder.

Hi mendonsy,..care to share an example, I'm really interested in seeing a working file.
mb

in omron stepper motor application sometimes the ladder diagram we program make we smile

cheat the ladder diagram