Has anyone used Pulse Width Modulation for Output in Siemens PLC?

[Preeya]

Has anyone used PWM output? I have to write a program to provide pulsed output to a valve with variable cycle time and pulse width. It is a high speed application.

 

[Preeya]

I guess not!

 

[jvdcande]

I guess not!

Don't be so impatient! Most of us have something else to do but hang out here all the time. I visit this site mostly once a day, sometimes twice. As a PLC instructor I always tell my trainees about this site, telling them they might expect an answer within 24 hours. You seem to give up on us after only 4 hours 58 minutes. Give us time!

First of all, if you want an answer you have to provide us with ALL necessary information. What Siemens PLC do you use? There's Siemens S5, with the various families like S5-100U, S5-115U, S5-135U. Then you have S7-200 and S7-300/400. These are not only two families, but completely different families. Even the CPU type can make a difference.

Kind regards,

 

[DesertDog]

I'm looking into a similar issue and haven't found anything yet, but I have just been informed this may be found in the Simotion line instread of the Simatic line. I'll let you know if I find more.

 

[Lark]

I have used both the PTO and PWM instructions on a high speed textile machine application, but with a ALlen Bradley controller. But I guess it shouldnt matter as long as you get the basics AND the specifics correct. Is there anything I can help you with?

 

[Preeya]

Yes I should have been patient! Happy to get some responses.

This is dosing application and I am going to use Siemens S7 200 PLC. I need to open and close a solenoid valve at speeds less than 30 ms. The pulse width and the cycle time of the output is entered by the user. So I plan to use PWM.

I read in the manual that outputs Q0.0 and Q0.1 can be configured to handle high speeds. My question is if the outputs are configured to operate that way is there a way to disable high speed operations based on a condition.

Thanks for all the responses

 

[kamenges]

I may not fully understand your application so this may not apply.
The PWM function will put out a continuously repeating pulse train at the cycle time and pulse width you specify unless you inhibit the output or you write zero to the pulse width. If you are trying to achieve quasi-analog control with a digital signal, PWM is the ticket. If you want to send out occasionally triggered pulses with the operator entered specifications PWM is probably not what you want.

Keith

 

[dchartier]

Hello;
I suggest you go to the Siemens support webpage and download the S7-200 Tips and tricks file. It contains tips (and actuakl programs) on using DC outputs inm PWM mode fpor the S7-200 CPUs (Look at tip #7, I believe). You should also download the S7-200_e.pdf manual to help you with the instruction list.

Go to the following link:
http://www4.ad.siemens.de/WW/llisapi.dll?func=cslib.csinfo&lang=en&objID=4000024


Hope this helps,
Daniel Chartier

 

[JPesh]

can you send me the link you refer to. It doesn't show up on your post.
[email protected]

Thanks