Query about cross-triggering multiple oscilloscopes (Analog Discovery 2s or OpenScopes)

[RossK]

Hello,

I am looking to design a data-logging system to monitor six channels, shown in the image below as A through F, these all being BNC connections.

The scopes monitoring channels A and B are the primary scopes and trigger on pre-set peak-to-peak magnitudes. Once those trigger they cross-trigger a combination of the other scopes. When scope A triggers it cross-triggers scopes C, E and F. When scope B triggers it cross-triggers scopes D, E and F. The scopes are depicted as having single inputs, but could have multiple inputs each so long as the required triggering requirements are met (for instance E and F can easily be monitored by one scope with a single trigger).

With the intended design explained, I have several questions:
1)    Would such a design be possible using some combination of Analog Discovery 2s and/or OpenScopes?
2)    Ideally I would like to be able to edit the trigger points for A and B without interacting with the GUI (this system is intended to be a headless data logger) and run one instance of the software to monitor all of the scopes (to minimize CPU load). Is that possible with the standard WaveForms or WaveForms Live software or could I perhaps write in the functionality in WaveForms scripting or by modifying WaveForms Live?

Any input would be greatly appreciated.

Thank you

 

 

[attila]

Hi @RossK

You could use Analog Discovery and/or OpenScope for this purpose. It depends on your requirements. See the reference pages:
https://reference.digilentinc.com/reference/instrumentation/analog-discovery-2/start
https://reference.digilentinc.com/reference/instrumentation/openscope-mz/start

Both devices have trigger IOs for synchronization.
The WaveForms application can control one device at a time, so you have to open separate instances for each device or write custom application or script using the WaveForms SDK.
The application features can be explored in demo mode and the SDK is included in the installer with manual and examples. https://reference.digilentinc.com/waveforms3
I'm not familiar with OpenScope, I will let @JColvin to comment on it.

[JColvin]

Hello,

If you have multiple instances of WaveFormsLive open, you can have each one connect to their own device over WiFi. It's technically possible to do something similar over USB, but from what I have been told the Digilent Agent has been hardcoded to avoid situation, so we don't recommend going down that path.

In terms of having one trigger on a piece of hardware trigger an acquisition on another piece of hardware (via a connected digital line or something similar), it is possible to do, but because it will all be over WiFi, the associated timing and delays will not be very...clean.

Otherwise, you could add in some of your own features for triggering by manipulating/creating your custom web as described here. There is also a command set you could use that is JSON based (link) though another Forum member created a Python based module for it as well if you prefer that.

Thanks,
JColvin

[RossK]

I think the Analog Discovery or Discovery 2 would be overkill for this application. We typically sample at about 20k samples/s, so the sampling rate and bandwidth of the OpenScope would be more than enough. It would, however, need BNC connectors to interface with the system. Is the BNC Adapter Board compatible with the OpenScope?

I have a bunch more questions if you have a minute 

1) For the software side, would I be able to modify the software to allow a single instance to interface with multiple scopes simultaneously? As this will be a headless data logger, there is no need for it to display the traces, just log the data when each scope is triggered.

2) Would channels be able to trigger independently but concomitantly? i.e. CH A and B are both active with different trigger levels.

3) If multiple scopes can be controlled with a single instance of the software, would it be possible to avoid the logic channel cross-triggering and have this done in the software? i.e. when CH A triggers, the software records A, C, E and F. If CH B triggers it records B, D, E and F?

4) If such software cross-recording is not possible, can the OpenScope generate a logic signal output when triggered and another OpenScope be set to trigger on that logic signal input?

 

Thank you

[JColvin]

Hi @RossK,

I am finding out if my answers are correct before submitting them since I didn't create the WaveFormsLive software and personally have not played around with it in this way, so I'd like to avoid giving false/misleading information if I can.

Thanks,
JColvin

[Kristoff]

Hey,

You could use the Digilent Instrumentation Protocol (DIP) to control the OpenScope.  Details here.

You could also create your own GUI or fork WaveForms Live as described here.

However, what you described would require a lot of complicated customization.

1) For the software side, would I be able to modify the software to allow a single instance to interface with multiple scopes simultaneously? As this will be a headless data logger, there is no need for it to display the traces, just log the data when each scope is triggered.

• You could create your own GUI to control multiple devices, but it would be a ton of work.  A lot of the low level services in WaveForms live are designed to handle multiple devices, but the high level UI does not support connecting to multiple devices at the same time.  

2) Would channels be able to trigger independently but concomitantly? i.e. CH A and B are both active with different trigger levels.

• OpenScope hardware / firmware only supports arming a single trigger source at a time.  Each OSC channel counts as a source, and any combination of LA channels is a source.  So you would need to modify the OpenScope firmware to accomplish this and it would not be easy.

3) If multiple scopes can be controlled with a single instance of the software, would it be possible to avoid the logic channel cross-triggering and have this done in the software? i.e. when CH A triggers, the software records A, C, E and F. If CH B triggers it records B, D, E and F?

• You can can arm the trigger and send a 'force' command in the same packet.  This is the equivalent of a software trigger.

4) If such software cross-recording is not possible, can the OpenScope generate a logic signal output when triggered and another OpenScope be set to trigger on that logic signal input?

• The hardware is capable but the firmware does not implement this.

Let us know if you have more questions.  Sorry I didn't have an easier solution for you

 

-Kristoff