PXI5112: Reconfigure during aquisition

[olifri]

Hallo,

I need to readjust the trigger level while an aquisition is running.

I've tried this with the TriggerLevelProperty, but it didn't work. Is there a way to do this.

More generally!

a) Which parameters are adjustable during aquisition, TriggerLevel apparently not (also sample rate, i tried this, too)

b) Is there a way to abort a running aquisition without resetting the timestamp counter?

Thanks a lot

Oliver Friedrich

[Josh H]

Hello Oliver,

Adjusting the digitizer's settings while an aquisition is in progress is not possible. You need to call the NI-SCOPE Abort function, change the settings appropriately, and then Initiate the acquistion with the new settings. This does not reset the absolute timestamp counter. Reset (and Close depending on the hardware) is the only way to reset the timestamp counter.

-Josh

[olifri]

Hallo Josh,

thank you for your efforts in helping me.
You said: Abort doesn't reset the timestamp counter. I'm afraid to tell you, it does. It is written in my NIScope user manual and I've verified it on my system.

Generally I have to say, that I'm very disappointed by the NIScope driver. First of all I've encountered a lot of problems due to instable behaviour when NIScope has to serve several threads, although it is claimed to be multithreading capable and reentrant. I wanted to operate my four digitizers by four threads, but after a lot of hazzles I gave it up sacrifying performance the 5112 hardware may offer.
Second there are a lot of restrictions which are not intuitive to me, like the timestamp counter problem, being unable to adjust the trigger while aquiring (any scope you take would allow turning on the level knob while waiting on a trigger) or the missing ability to or together both channels as trigger source (most likely more a 5112 issue).

But it's useless to moan about spilled milk, I'm sure you are not responsible (or are you ???)

Thanks

Oliver Friedrich

[Josh H]

Oliver,

I apologize because I did state that falsely. The NI 5112 does in fact reset its timestamp counter when Abort or Close is called, however the NI 5122 and our SMC based products do not. These new products also support many advanced options that the 5112 does not, such as the ability to synchronize and trigger independently without the use of an external device to calibrate the absolute timestamp counters.

I am also sorry the NI-SCOPE driver has not met your needs. I would appreciate any constructive feedback you might have. I will try to answer some of your concerns here.

"any scope you take would allow turning on the level knob while waiting on a trigger"
This is actually not true. Oscilloscopes acquire data in the same fashion that we do. When you turn the knob on a scope, it is not changing the trigger for the current record. It's actually changing it for the next record that you acquire. What appears to be continuous acquisition on an oscilloscope is really just multiple records of usually small sample sizes.

"the missing ability to or together both channels as trigger source"
The ability to trigger both channels independently from one another is a hardware feature that is currently not implemented on any of our digitizers. However, you can synchronize several boards together to achieve this capability.

Best regards,
Josh

[olifri]

Hallo Josh,

it is very good talking with you. But now I think it's time to call the thread closed. Maybe we could keep in contact by email.
Try oliver.friedrich@tzm.de

Best regards
Oliver