DT9816 single analog value acquisition on trigger

[glejeune]

Hello,

For my application using the DT9816:

I would like to make a single analog input acquisition (1 sample) on every rising edge of a TTL signal.

I have started to read the DP-Open Layers for .NET documentation but there is a lot to take in.

Could you give me a head start or some advice to realize this task? Such as telling me some of the functions that i could use or maybe give me an example.

Should I use the TTL EXt trigger or maybe an event on a digital pin?

Thanks in advance.

Best regards,

Gary

 

[Fausto]

Hello @glejeune.

The DT9816 Series does not support an external trigger input for single values, nor does it support a digital event on the input trigger.  

User's Manual:  https://www.mccdaq.com/PDFs/Manuals/UM9816.pdf

 

In your code, you could have a loop that is polling a digital input bit.  When the bit is at a high level, then call a single value read on the analog input channel.  An edge transition is not supported, so if the bit remains high, for additional loops, then it will read additional analog input values until the bit is at a low level.

DT-Open Layers for .NET Class Library User's Manual:  https://www.mccdaq.com/PDFs/Manuals/UMOpenLayers.pdf

Chapter 5 in the DT-Open Layers for .NET Class Library User's Manual presents programming flowcharts for single-value analog input operations and single-value digital input operations. 

After installing Data Translation's OMNI software, the .NET examples will reside in the 'C:\Program Files (x86)\Data Translation\DotNet\OLClassLib\Examples' folder, while the Win32 SDK C examples reside in the 'C:\Program Files (x86)\Data Translation\Win32\SDK\Examples' folder.

DT OMNI software link folder:  https://mcc.download.ni.com/#downloads/DTSoftware/Omni-CD/

 

Regards,

Fausto

[glejeune]

Hello Fausto,

Thank you for your answer.

I am afraid that polling a digital input to trigger a software trigger for the conversion will be too slow for my application.

This is because I have to measure the peak voltage of fast pulse (~10µs) at the output of a peak and hold circuit.

In other words in need to acquire the signal very shortly after the TTL signal rising edge. Is that possible using the DT9816? In all honesty I may have chosen the wrong device for my application.

Wouldn't it be possible to use the continuous scan mode, trigger the scan start with the Ext trigger while using a buffer a small size?

Thanks in advance.

Regards,

Gary

[Fausto]

Hello Gary.

You could use an external trigger to start a continuous acquisition.  Additionally, you could connect your digital signal to an available analog input channel and capture those signals simultaneously.  You would require some post processing to determine where the digital levels changed, in order to determine your signal's voltage level.

Regards,

Fausto