PCGU1000 PWM duty cycle <10% or >90% possible?

Instruments PC Generators
1

Hi Velleman support,

we are using PCGU1000 function generator with PCLab software (current version from web page). We would like to generate PWM signals with duty cycle below 10%, but the software seems to be stuck at min 10% (and also max 90%). Is there a reason for this? Could this possibly get extended to 0% (or “just close to zero”) and 100%?

Thanks, Jorg

2

There is no actual reason to limit the duty cycle range to 10%-90%.
In the new software release the range is now expanded to 1%-99%.
Here is the link to download the updated PcLab2000SE version 4.04: box.net/shared/c9nis5ro05if3oop9ptk

3

Wow, thank you very much for the super fast reply. I will test this shortly! :smiley:

Do you think an even finer resolution of duty cycle setting would be possible, e.g. starting from 0.1% in 0.1% increments to 99.9% ??
We are currently testing model servos, and here the useful signal varies in a range between ~0.7ms and ~2.3ms, with an overall PWM cycle length of 20ms. So currently, our fine adjustment is 0.2ms (==1% of 20ms), but we would prefer to have even finer control.

Thank you very much! Best regards,

Jorg

4

Sorry, there are some practical software problems to use values below 1% and beyond 99% in the PCGU1000.

As an alternative “workaround” you can use the library waveform to get more PWM ratios.
It is very easy to create the waveform library file using the Wave Editor of the function generator software.
Here is an example of the waveform file how to get 0.1% duty cycle:

1.0 (10) (0) -1.0 (9990)
And this is the waveform file for 0.2% duty cycle:

1.0 (20) (0) -1.0 (9980)
You can use copy and paste in the Wave editor’s edit window to copy the data there.

In the PCGU1000 the maximum number of samples per one period is 8192.
The software resamples the values of the wave file to fit to 8192 samples per period.
Due to this resampling there may be some error in the final duty cycle.

The “(0)” in the data file is to get sharp pulse edge…
Please see the Help menu of the Wave Editor for more details how to create the custom waveform files.

5

Problem solved. Now the duty cycle can be adjusted in steps of 0.1% from 0.1% to 99.9%.
Here is the link to download the updated software: box.net/shared/c9nis5ro05if3oop9ptk