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Sampling using own software: picolog1216

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Sampling using own software: picolog1216

Postby aeroplanino » Fri Nov 13, 2015 7:49 am

Hello all,

I am new to picolog - having just come across the 1216 data logger recently. I wanted to ask if it is possible to sample data from devices connected to all 16 channels of the data logger taking one reading from each device in turn for example at a sampling rate of 100µsec per channel?
To extend this further is there even a possibility to take simultaneous reading from all 16 channels for the sake of synchronization?

And which kind of sampling mode would be appropriate for this scenario or is the sampling mode chosen is related to the way I require the data to be transferred to the PC rather than the order of sampling on the data logger?
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Re: Sampling using own software: picolog1216

Postby Hitesh » Wed Nov 18, 2015 11:29 am

Hi aeroplanino,

The maximum sampling rate in continuous streaming mode is 100 kS/s shared by all channels when using the SDK so you should be able to use the pl1000SetInterval function to specify a total number of samples between all channels in a specified period of time to achieve 10kS/s. Please note that the driver will not return the actual sample interval used.

The driver will populate an array with the data values collected from each channel in sequence e.g.

Ch 1, Ch 2, Ch 3, Ch 1, Ch 2, Ch 3 and so on.

Unfortunately it is not possible to collect data from each channel simultaneously.

If you are looking to collect a number of samples greater than that available in the memory of the device, I would suggest using streaming mode capture.

Hope this helps.
Hitesh

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Re: Sampling using own software: picolog1216

Postby aeroplanino » Tue Dec 01, 2015 8:47 am

Hi Hitesh,
Thank you for answering my question. Yes I am looking for to capture a number of samples greater than that available in the memory of the device, and unfortunately I also require the sampling rate between successive samples in two channels to be much faster than 10µs (e.g 2µs between samples in consecutive channels); if I did not get it wrong the fastest sampling time in streaming capture mode is 10µs.

Is there any way I can use the BM_SINGLE capture mode to utilize its faster sampling rate and still capture a number of samples greater than that available in the memory of the device?

I have also one more question, the pl1000Run function accepts the number of samples to acquire and the pl1000Ready function indicates when that number of samples have been acquired. I am a little confused as to how the internal memory buffer does not get overwritten if the number of samples set as a parameter in the pl1000Run function is greater than the 8192 sample buffer size of the device?

Thank you again for your reply.
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Re: Sampling using own software: picolog1216

Postby Hitesh » Thu Dec 03, 2015 12:38 pm

Hi aeroplanino,

The fastest possible sampling interval when capturing data in streaming mode is 100kS/s. If, for example, 2 channels are enabled, this would give you a maximum rate of 50kS/s per channel.

Having run tests here, when using the BM_SINGLE capture mode, you can capture more samples than the actual buffer size of the device as the data is repeatedly transferred to the driver where it is held until the call to pl1000GetValues() is made.

The following is written in the Programmer's Guide in relation to streaming:

BM_STREAM is useful when you need to collect data continuously for long periods. In
principle, it could be used to collect data indefinitely. Every time pl1000GetValues is
called, it returns the new readings since the last time it was called.

As mentioned above, the driver holds the data values until requested, so you can specify a number of samples greater than the buffer size and the driver will return the latest values collected since the last request.

Hope this helps,
Hitesh

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Re: Sampling using own software: picolog1216

Postby aeroplanino » Fri Dec 04, 2015 12:15 pm

Hi Hitesth,
Thank you for the reply and also for your email.The information is quite helpful. Thanks again for taking the time to go through my inquiries.
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