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AUX trigger in labview

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AUX trigger in labview

Postby Robobix » Wed May 01, 2013 8:51 am

Dear PicoTech

I purchased a PicoScope6403A for the intended use for long term recordings multiband laser-radar echoes. The laser radar emits pulses at 10Hz repetition rate, and the plan is to record the echoes in 4-bands at 1GHz (downsample ratio 5 -> "12bit"), with some 100.000 sample points in each channel (before downsampling). I verified that I am not able to automatically store the returns using the PicoScope6 software. I then fought to implement this rather simple case in Matlab through the DLL but got lost in the huge amount of incorrect trigger settings and weird library pointers. Eventually I turned the frustrating wire-ring of LabView and almost got it to work. I used the most recent software development kit and the PicoScope6000ExampleBlock.vi.

Everything works as supposed to, the only problem is that I am unable to change the trigger source to the AUX input on the rear panel. I connected one of the probes from the probe calibration output to the AUX and another probe from calibration output to Channel A to verify that triggering works. I tested the functionality in PicoScope6 software and selected AuxIO as trigger source and it works. In the LabView example I went into the TriggerSettings cluster and investigated the TriggerSource dropdown. The dropdown doesn't have any AUX option and outputs integers from 0..3 according to the channel choice which are apparently fed into the ps6000SetSimpleTrigger in the sub-VI by calling a picostatus block. In the manual it is stated that the trigger source can be string values of e.g. "PS6000_CHANNEL_A" etc. and also "PS6000_TRIGGER_AUX" but there is no mentioning of what integer correspond to what. In the enumeration "PS6000_TRIGGER_AUX" appear on the zero-based seventh row, so I attempted to edit the values of the TiggerSource dropdown and tried both with the integer 4 and 6 but none of this works. Besides the trigger threshold level is given in int16 counts, and i have been unable to find the voltage range of the AUX input to rescale that, but I scanned through all of the values in order to find a stable triggering with no luck.

I appreciate any urgent solutions as I will travel to the laser radar station in Greece next week to install the sampling board.

Kind regards, Mikkel Brydegaard
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Re: AUX trigger in labview

Postby Hitesh » Wed May 01, 2013 3:31 pm

Hi Mikkel,

The enumeration numbering changes due to the PS6000_MAX_CHANNELS = PS6000_EXTERNAL line.

Therefore, please use the integer value 5 for the Auxiliary Input. The maximum input voltage is +/-5V and the input threshold is +/- 1V.

I believe the max ADC count should be 32767 to help with converting to voltage for the Aux input.

Please post your vi here or e-mail support@picotech.com if this does not work.

It is possible to create MATLAB scripts to control the scope - please see http://www.picotech.com/support/topic10809.html

I hope this helps.

Regards,
Hitesh

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Re: AUX trigger in labview

Postby Robobix » Fri May 03, 2013 7:34 am

Dear Hitesh

Thank you for the assistance. I got everything to work all-right. Actually I had to change the drop down items not only in the ps6000exampleblock.vi but also in the ps6000settings block, because the number didn't propagate inside the block.

kind regards,
Mikkel
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