Simultaneous data recording from multiple DAQ HATs

[Saha]

Hello,

 

I want to record data using mcc128 (single-ended) and mcc172 (differential values) at the same time. The output should be two numpy array from two acquisition systems. Can you please guide me how to accomplish this? 

 

Thank you.

 

#mcc #daqhats #python

[Fausto]

Hello @Saha.

While it is possible to capture data on both boards, using the same application, the MCC 128 and the MCC 172 do not support synchronized capture of data between the two boards.  The MCC 128 uses a successive approximation A/D converter type, while the MCC 172 uses a delta sigma A/D converter type.  The MCC 172 samples can only be synchronized with other MCC 172 boards due to the type of ADCs used.  The delta sigma converters have a sampling clock rate much higher than the data rate (512x).  The MCC 172's sampling clock uses a 26.2144 MHz clock, which can be divided down by a microcontroller to get lower sampling rates.  The MCC 172 sampling rate must be integer divisors of 26.2144 MHz / 512.

The clock & trigger syncing with the MCC 172 through the RPi GPIO header allows multiple MCC 172 boards to use the same 512x ADC clock and trigger signal so that all the ADCs will start converting at the same time and run from the same clock, resulting with all subsequent samples in sync.  This clock cannot easily be used for other ADC boards (i.e. MCC 118, MCC 128), because of that high rate.

Refer to the MCC 172 example, fft_scan.py, for an example that uses the Numpy library and alter the example to suit your application's needs.  Python examples for the MCC 128 are located here.

 

Regards,

Fausto

Edited February 6 by Fausto
updated response