SLew rate automatic display


Sorry if my question has already been dealt with in another post OR if the feature I’m looking for already exist (but I did not find it).

I’ve a PCSU1000, and the wave form Parameter box is really usefull.
I’m looking for the “slew rate” but cannot find it clearly displayed.

there is already the “rise time” and the “fall time” computed using High reference an Low Reference (90% and 10% of the amplitude of the signal). That is great !
But the “High reférence” is not displayed , and there is only the "High Value " which is not the same (with my understanding of the help document).

I suspect that it is possible to get the High reference value displayed and another kind of indicator called slew rate “rise” computed as : (high reference - Low reference)/rise time.

Obviously I can do it manually, but knowing that these values are accessible, it would be great if it was directly computed/displayed automatically.

if this feature does not exits “as is” it would be nice to have :slight_smile:

Thanks in advance for your support. Gilles.

It’s nice that you like the features of the Waveform Parameters display!
Thank you for the suggestion to improve the software for the PCSU1000.

Indeed, to keep it simple, there are now only commonly used parameters displayed on the Waveform Parameters window. The Slew Rate is missing. Also the reference levels for Rise Time and Fall Time are not displayed.

The reference levels for Rise Time and Fall Time are 10% and 90% of the Amplitude reading.
Thus, the voltage change is 0.8 * Amplitude.
And the Slew Rate is:

Slew_Rate = 0.8 * Amplitude / Rise_Time

thanks, for this.

I will use this formula - that’s much easyer than what I was doing.

Best regards gilles.

One general suggestion to the measurement setup: It would be very helpful if there were an option to define which thresholds to use for e.g. rise/fall time measurements. Typical options found on other scopes are:

relative to waveform high/low levels:

  • 10%/90% (like the current default in PCLab)
  • 20%/80% (should be easy to add)
  • user defined percentages


  • enter absolute voltage levels for crossing points (e.g. 1V/4V)

For delay, period and frequency measurement the user would need to define the threshold level in a similar fashion (e.g. either 50% between high and low level, or absolute)

The settings should be independently settable for the two channels.

All this could be put onto a separate panel, with defaults set the same as it is now (so an inexperienced user would not need to set anything and would get the same functionality as the program provides now).


Thanks womai for this suggestion.
Now there is added an Options button to the Waveform Parameters window.
A second dialog will appear.
There you can:

  • switch between 10%/90% and 20%/80% for the rise time thresholds
  • switch between 25%, 50% and 75% for pulse width and duty cycle measurement threshold

Both of these thresholds are independently settable for the two channels.

The voltage level selection for the thresholds is very difficult to implement. The software handles only the raw data (0…255). All the thresholds and time calculations are based on the raw data.
The only where the voltage and time values are calculated is just to print them to the Waveform Parameters window.

Here is the link to the setup file:


this is great - I keep being impressed by your fast response time. I fully understand that some features that seem to be easy addition from the outside can be difficult to implement because of software internals - I am developing software myself and run into this often enough.

I noted that it may be good to have more levels to select the middle threshold.
Here a snippet from the updated help file:

Click this button to open the Threshold Options dialog.
There you can:

  • Switch between 10%/90% and 20%/80% for the rise time and fall time thresholds (Low reference and High reference).
  • Switch between 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 95% for pulse width and duty cycle measurement threshold (Middle reference).
    Both of these thresholds are independently settable for the two channels.[/quote]
    The selected thresholds are remembered (in WinDSO.ini) to the next session.
    Here is the link to the updated setup file: