Test and Measurement Forum

Using multiple Scopes synced with LabVIEW

Post your LabVIEW discussions here

Using multiple Scopes synced with LabVIEW

Postby Maik1976 » Tue Aug 01, 2017 8:32 am

I'm using three of the PicoScopes (5444B) to capture 11 signals.

How can I synchronise the three captures. I need all of them with the exact same trigger impuls.
It is configured with external trigger line and all connected together to the sync out of my generator.

With "normal" scopes I arm them all to single shot and it works the all capture at the same trigger and then I can read aut the data. Here the arming of the second device is happening after the readout of the first one.
This mode is useless.

In my result the signal of Channel C is not in sync and to noisy. It is generated by a signalgenerator and direct connected with BNC-Cables.

How get I it in sync?

Greets
Maik
Attachments
pico_front.png
Frontpanel with result
pico_back.png
Back panel of code
Maik1976
Newbie
 
Posts: 0
Joined: Tue Aug 01, 2017 8:17 am

Re: Using multiple Scopes synced with LabVIEW

Postby Hitesh » Fri Aug 11, 2017 11:51 am

Hi Maik,

Please note that true synchronisation between the PicoScopes is not possible as the Analogue to Digital Converters could be operating at slightly different frequencies. You can still trigger each device using a common signal though.

The reason why the LabVIEW code waits for to collect data from the first device before the next is because the sub-vi that handles the block capture contains the code that starts the capture, polls the device and requests the data.

You will most likely need to copy the code out of the sub-vi and modify it to start all three devices collecting data then poll all three (using the Call Function Library Node that calls ps5000aIsReady()) to see if they have completed data collection before retrieving the data.

Please note that you will need to call the functions for each device using the correct handle value and parameters.

Hope this helps,
Hitesh

Technical Support Engineer
Hitesh
Site Admin
Site Admin
 
Posts: 2490
Joined: Tue May 31, 2011 3:43 pm
Location: St. Neots, Cambridgeshire

Re: Using multiple Scopes synced with LabVIEW

Postby Maik1976 » Wed Aug 16, 2017 7:52 am

Hi,
the problem with the internal adc frequency I know. For my problem it is not so important.
BTW: Professional tools have a 10 MHz input or sync to the USB heartbeat. I further project I worked on, synced (frequency and phase of internal osc. ) over USB to 10ns accuracy every 6 seconds.

But here the other problem is, that the dll-function in this labview-"driver" for starting the sampling is also blocking until all data are transferred. This dll-function combines two basic functions.
Maik1976
Newbie
 
Posts: 0
Joined: Tue Aug 01, 2017 8:17 am

Re: Using multiple Scopes synced with LabVIEW

Postby Hitesh » Fri Aug 18, 2017 8:42 am

Hi Maik,

But here the other problem is, that the dll-function in this labview-"driver" for starting the sampling is also blocking until all data are transferred. This dll-function combines two basic functions.

Could you please clarify the above?

Are you referring to the ps5000aRunBlock() and ps5000aIsReady() functions being in the same sub-vi? If so, you will need to separate the code out for your application purpose.

Regards,
Hitesh

Technical Support Engineer
Hitesh
Site Admin
Site Admin
 
Posts: 2490
Joined: Tue May 31, 2011 3:43 pm
Location: St. Neots, Cambridgeshire


Return to LabVIEW

Who is online

Users browsing this forum: No registered users and 1 guest