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Logging using ADC212 and a trigger

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Logging using ADC212 and a trigger

Postby huxy » Mon Nov 24, 2003 9:39 am

I have a signal coming into the ADC212 which I want to capture, but only when the trigger is high as the data is invalid at other times. I can't work out how to set this up in picolog :-(

The specifics are :-
Signal is valid for approx 600 us and then not for 30 us.
I want to catch a couple of points (or at least one) on the 600 us plateau.
It needs to run for a couple of minutes.
The trigger can be moved around but is high for the duration of the valid data.

Can I do this?

Any help much appreciated.

Cheers,

Hux
huxy
 

Postby markspencer » Tue Nov 25, 2003 8:25 am

Hi,

You certainly can trigger the ADC-212 when the signal reaches a threshold amplitude, unfortunately you will only be able to collect data for seconds rather than minutes. The reason for this is that the unit will only sample until the buffer is full and then download the data. The length of time that it will sample for is determine by the time interval that you choose.

To do the above select:

File | New Settings

In the recording window select 'fast block mode', then click OK, (then select the unit, if not predefine). Now set the channels that you require, the sampling interval, oversample and the number of samples. In the top right corner it will give you a guide of how long the run will be.

Now to set the trigger click on the trigger button; enter the threshold voltage, channel it is to trigger off, delay (if required), direction and if you do not want auto triggering then remove the tick from the box. Lastly click the 'enable trigger' box.

The auto trigger will fire if no signal has been recieved with in the time period stated.

I hope this helps.

Best regards
Regards,

Mark Spencer
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Postby Amy » Thu Dec 04, 2003 11:32 am

It is possible to use Labview to obtain a continuous stream of data rather than data blocks?
Amy
 

Postby markspencer » Fri Dec 05, 2003 8:25 am

Hi,

Unfortunately, it is not possible to do it in any third party application, since these all rely on the units windows driver. Everything I said in my previous answer is applicable to Labview as well.

Best regards,
Regards,

Mark Spencer
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Postby Amy » Fri Dec 05, 2003 12:24 pm

Hi,

I am currently using the adc200.vi as a sub vi in LabView to capture my data for processing. I am using both channels on the ADC212, one for data and one for a trigger signal. The idea is to use the trigger event to capture a specific range of data. However, because the data from the ADC212 is in blocks at random points in time, the triggered (cropped) data string keeps changing size. Thus when I collect in data from 50 trigger events for averaging, I get false readings. Is there any way round this?

Is it possible to enable the adc200.vi to collect blocks of data at the rising edge of a ramp signal?

Thanks,

Amy
Amy
 

Postby markspencer » Mon Dec 08, 2003 8:53 am

Hi,

Unfortunately, I do not quite understand what you are doing, expecting to get from the triggering and the actual results that you are receiving.

Could you please provide further details explaining what you are doing the type of signal that you are triggering off, what you mean by false readings, 'data string changes sizes' once I can get a better understanding of the situation I will be in a position to help.

Best regards,
Regards,

Mark Spencer
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Postby Amy » Mon Dec 08, 2003 10:26 am

Hi,

I am trying to use the adc.vi to capture two signals, a data signal and a trigger signal. At present, the adc.vi captures blocks of data at random points in time, however, I require the adc.vi to capture blocks of data at the rising edge of a ramp signal. Is this possible? If so, what is the best method to achieve this?

I found a routine called adc200_set_trigger which I think enables the adc.vi to begin capturing a block of data only when a trigger event has occurred, however, I cannot find the appropriate types in the Call Library Function Node configuration box to match the parameter types of the adc200_set_trigger.

Thanks,

Amy
Amy
 

Postby Amy » Mon Dec 08, 2003 3:02 pm

Hi,

It's o.k, I've managed to solve the problem.

Amy
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