Real sample rate of MCC134 does not reach 1 S/s

[Daniel Deng]

Hi, 

I ran this Python code to collect temperature data from the MCC 134 every second. However, I noticed that every 3 to 4 samples, there are two consecutive seconds that read exactly the same temperature data. It seems that the actual sample rate of the MCC 134 is slightly less than 1 S/s, because when I set time.sleep(1.5), the data varies between any consecutive samples.
 

Could you possibly test the actual sample rate and let me know if there's any way to ensure that the actual sampling rate reaches 1 S/s?

Thank you.

Edited October 3, 2024 by Daniel Deng
Make the question clearer

[Fausto]

Hello @Daniel Deng.

The MCC 134 has a maximum sampling rate of 1 Sample/sec (best case scenario of single reads in a tight loop).  Each sample is captured as a single value and a continuous scan capture (while available on some other DAQ HATS) is not supported on the MCC 134.  The effective capture rate is system dependent.  The more background processes running, the number of MCC 134 boards enabled, the number of enabled channels on each board, and your code all affect achieving the maximum sampling rate.

Are you using a RPi 5 module with the Raspbian Bookworm OS and 8 GB RAM?

Regards,

Fausto

[Daniel Deng]

On 10/4/2024 at 5:40 PM, Fausto said:

Hello @Daniel Deng.

The MCC 134 has a maximum sampling rate of 1 Sample/sec (best case scenario of single reads in a tight loop).  Each sample is captured as a single value and a continuous scan capture (while available on some other DAQ HATS) is not supported on the MCC 134.  The effective capture rate is system dependent.  The more background processes running, the number of MCC 134 boards enabled, the number of enabled channels on each board, and your code all affect achieving the maximum sampling rate.

Are you using a RPi 5 module with the Raspbian Bookworm OS and 8 GB RAM?

Regards,

Fausto

Yes. I am using RPi 5 and 8 GB RAM. I found in other posts that there is a hidden limit on the sampling rate of MCC 134, which is around 1.5 S/s, but it's acceptable to me. Thanks for your response.