Frequency Response Analyzer with Bode Plots

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avi.patel001
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Re: Frequency Response Analyzer with Bode Plots

Post by avi.patel001 »

hexamer wrote:
Thu Nov 05, 2020 12:36 pm
avi.patel001 wrote:
Wed Nov 04, 2020 5:30 pm
So What is the method to use this software? What I have followed,
1) COnnect the USB of picoscope and open picoscope 6 software
2) open the Fra 4 picoscope software and go to file>connect the scope (When I select that option it says me no compatible picoscope device found)

Am I following the right method? or Am I missing something?

Thanks
Avi
Avi,

You should not be opening the PicoScope 6 software. The FRA app is independent of the scope app. By opening the PicoScope 6 software, the scope is not accessible to the FRA App because only one application can access the scope at a time.

The FRA app uses the Picotech SDK, which is in the form of DLL files. It turns out that the PicoScope 6 software also provides these SDK files in its installation directories. So sometimes (though it's not advised) you don't have to install the SDK. The SDK version of these DLLs is preferred because it's what I test to.

Thanks,

Aaron.
Oh, Thank you so much, Aeron, for the help; I am very beginner at the picoscope. I have just tried to use a signal generator, so I connect it, but I don't know how to set it up. When I select the "built-in" option, it says "Signal Generator plugin not configured." When I select the "External" option, it asks for plugin name in dll form, Instrument ID, Initialization. Can you please guide me so I can use AWG from FR4PicoScope?

Thanks
Avi

hexamer
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Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

avi.patel001 wrote:
Thu Nov 05, 2020 7:08 pm
Oh, Thank you so much, Aeron, for the help; I am very beginner at the picoscope. I have just tried to use a signal generator, so I connect it, but I don't know how to set it up. When I select the "built-in" option, it says "Signal Generator plugin not configured." When I select the "External" option, it asks for plugin name in dll form, Instrument ID, Initialization. Can you please guide me so I can use AWG from FR4PicoScope?

Thanks
Avi
Avi,

You should not need to configure for an external signal generator and it's unlikely you were able to do so. The default configuration will use the PicoScope's internal signal generator.

If your having issues, this post from Wim provides some good advice and illustrations : viewtopic.php?p=141096#p141096

The picotech app note is also a good resource: https://www.picotech.com/download/broch ... n-note.pdf

Thanks,

Aaron

mransaw
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Re: Frequency Response Analyzer with Bode Plots

Post by mransaw »

whichislovely wrote:
Mon Sep 30, 2019 2:59 pm
Hello!

I am trying to use PicoScope5443D with the latest version FRA4PicoScope 0.6.2b.msi. I have two problems though.

1) There is a fatal error saying
"ps5000aSetChannel( 16384, 2, 0, 0, 0, 0 );Fatal error: Failed to disable channel: 290
Status: 5443D S/N: GX150/0121 successfully initialized."

2) When I try to set start frequency to be 100.0 it outputs the following error:
"Start frequency must be >= inf Hz
Error: Invalid inputs."
which confuses me.

Thanks in advance.
I am getting the same message using FRA4PicoScope 0.7.0b with a PicoScope 4824.
"Start frequency must be >= inf Hz
Error: Invalid inputs."

The 32-bit PicoScope SDK (10.7.18.140) is installed. When FRA4PicoScope first starts up it says
"Status: 4824 S/N: FZ013/155 successfully initialized."

If I click Connect Signal Generator and select Built-in, it says
"Signal generator plugin not configured."

Can anyone help to troubleshoot this?

Thank you,
Miles

hexamer
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Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

mransaw wrote:
Fri Nov 13, 2020 8:37 pm
I am getting the same message using FRA4PicoScope 0.7.0b with a PicoScope 4824.
"Start frequency must be >= inf Hz
Error: Invalid inputs."

The 32-bit PicoScope SDK (10.7.18.140) is installed. When FRA4PicoScope first starts up it says
"Status: 4824 S/N: FZ013/155 successfully initialized."

If I click Connect Signal Generator and select Built-in, it says
"Signal generator plugin not configured."

Can anyone help to troubleshoot this?

Thank you,
Miles
Miles,

I would be happy to help here, just would like to know some more details. Are you using the low noise mode (default) or noise reject mode? While you're getting back to me, I'll see if I can deduce what's going on here.

EDIT 11/16/2020: It seems the most likely cause for this would be that the ps4000aGetTimebase function is returning a 0 for maxSamples, causing a divide by 0. But the current source code is not setup to diagnose this specific possibility. To confirm this, I'd need to build a special version for you and ask you to turn on the API tracing diagnostics. Would you be willing to help me out?

Also, the message "Signal generator plugin not configured." is actually expected - though maybe not so intuitive. What it's trying to tell you is that you tried to connect an external signal generator (i.e. not the one in the PicoScope) and were not successful. To correctly setup an external signal generator you have to supply a DLL and parameters. Correct me if I'm wrong, but I assume you don't really want to setup an external signal generator. The default configuration of the app is to use the PicoScope's internal signal generator, which is what a vast majority of people will want to to (at least initially).

Thanks,

Aaron.
Last edited by hexamer on Tue Nov 17, 2020 1:11 am, edited 1 time in total.

hexamer
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Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

Andreas_ wrote:
Tue Nov 03, 2020 6:06 am
Hello Aaron,

do you plan to support (cheap) external function generators e.g. like the FY6800?
Would be nice to extend the frequency range to 60 MHz.

with best regards

Andreas
Hello Andreas,

You may know that I recently added an ability to extend FRA4PicoScope to allow for external signal generators using a modular (DLL) approach. The first example is based on a home brewed DDS I made based on a EME165-R2. I did this mainly to support another project I was pursuing at the time, and partly because external signal generators are a common request. To do it right, it needed to be modular given the many possible signal generators.

Given that I don't have access to other signal generators and have satisfied my immediate needs, I don't have any high priority plans to create other plugins. Longer term, I would like to further prove-out the extension interface. Likely candidates would be to support (1) common interfaces like SCPI or (2) like you mention, instruments readily accessible to hobbyists.

Thanks,

Aaron.

mransaw
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Re: Frequency Response Analyzer with Bode Plots

Post by mransaw »

hexamer wrote:
Sun Nov 15, 2020 4:16 pm
I would be happy to help here, just would like to know some more details. Are you using the low noise mode (default) or noise reject mode? While you're getting back to me, I'll see if I can deduce what's going on here.

Also, the message "Signal generator plugin not configured." is actually expected - though maybe not so intuitive. What it's trying to tell you is that you tried to connect an external signal generator (i.e. not the one in the PicoScope) and were not successful. To correctly setup an external signal generator you have to supply a DLL and parameters. Correct me if I'm wrong, but I assume you don't really want to setup an external signal generator. The default configuration of the app is to use the PicoScope's internal signal generator, which is what a vast majority of people will want to to (at least initially).

Aaron.
Hi Aaron,

I was using the low noise mode. I just tried the noise reject mode and it seems to work.

I am using the PicoScope's internal signal generator.

Thank you,
Miles

hexamer
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Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

mransaw wrote:
Tue Nov 17, 2020 12:20 am
Hi Aaron,

I was using the low noise mode. I just tried the noise reject mode and it seems to work.

I am using the PicoScope's internal signal generator.

Thank you,
Miles
Hmm, the plot thickens :) This points to some sort of initialization (or lack thereof) sequence issue.

Are the issues with low noise mode repeatable? Specifically, if you launch the app in low noise mode and try to run a FRA, does the "inf" error happen every time? If so, would you mind posting the results of a session with API tracing turned on? Tools->Settings->Log Verbosity button, turn on PicoScope API Calls. Try to run a FRA, then copy the log and post it here.

Emgu
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Re: Frequency Response Analyzer with Bode Plots

Post by Emgu »

Hello Aaron!

Thank you for this software!
We are using your software for characterization of a contact impedance and are using a reference resistor in series with our contact. So that they form a voltage divider. Channel A is measuring at output of the AWG and channel B is measuring between the DUT and the referece resistor.
I have a question about the operation of the software:
Does the "stimulus amplitude" refer to the voltage of the AWG or to the voltage between the two channels used for measurement? For our interests, ideally the voltage across the load should be kept constant along with the voltage of the AVG.
Kind regards
Emanuel

develx
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Re: Frequency Response Analyzer with Bode Plots

Post by develx »

Hello!

I'm evaluating to buy Picoscope 5244D for to analyze the frequency response of my SMPS prototype.
The 5244D model is supported at this moment by FRA4Picoscope?

Thanks in advance
develx

hexamer
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Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

Emgu wrote:
Fri Nov 20, 2020 11:33 am
Hello Aaron!

Thank you for this software!
We are using your software for characterization of a contact impedance and are using a reference resistor in series with our contact. So that they form a voltage divider. Channel A is measuring at output of the AWG and channel B is measuring between the DUT and the referece resistor.
I have a question about the operation of the software:
Does the "stimulus amplitude" refer to the voltage of the AWG or to the voltage between the two channels used for measurement? For our interests, ideally the voltage across the load should be kept constant along with the voltage of the AVG.
Kind regards
Emanuel
Hello Emanuel,

Thank you for your interest in the FRA app!

The "stimulus amplitude" refers to the voltage of the AWG. If you need to keep a constant voltage on the load, you'd need to try "adaptive stimulus" mode or "custom plan" mode, depending on how constant you need it to be.

Adaptive stimulus mode can control the stimulus amplitude to cause the input or output amplitude to track closely to a specified value. But it was designed with SMPS measurements in-mind. Given that, it works by seeking the minimum stimulus amplitude that still achieves the target output response of the input or output channel with the lowest amplitude response (I know ... quite the mouthful!) So, depending on the nature of the voltage divider, you may not be able to control just the voltage on the load. If the voltage divider is such that the voltage across one element is always larger than that across the other, this mode could work for you.

EDIT: One other point here is that in this mode, while seeking the best amplitude, the application can apply more voltage than the final target. I assume since you say your load is a "contact", that we're not concerned about physically damaging it? Perhaps your load's impedance is actually voltage dependent? Something I think often surprises people is that a ceramic capacitor's capacitance is voltage dependent. If you hookup a simple RC filter with a ceramic cap to the FRA app and run in custom plan mode with varying stimulus, you can easily see this effect on the response.

Custom plan mode is a way to define a stimulus amplitude based on frequency ranges. The main limitation here could be that it allows only up to 10 segments to be defined. Depending on how tightly you must control load voltage that might not be enough precision.

If you could give more details on the nature of the reference resistor and DUT, we can figure out a proper solution.

Thanks,

Aaron
Last edited by hexamer on Sat Nov 21, 2020 1:56 pm, edited 1 time in total.

hexamer
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Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

develx wrote:
Fri Nov 20, 2020 2:09 pm
Hello!

I'm evaluating to buy Picoscope 5244D for to analyze the frequency response of my SMPS prototype.
The 5244D model is supported at this moment by FRA4Picoscope?

Thanks in advance
develx
Hello develx,

While I cannot say that I've personally tested the 5244D, I will tell you that I own a PS5444A which I regularly test and they use the same driver family. The 5244D should be an excellent choice for SMPS measurements given its very large dynamic range and sample buffer. If you had any issues, I'm more than happy to help make it work for you.

Thanks,

Aaron.

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