MCC172 calibration value writed but not work

[Tik Sun]

Hi, I am using a MCC172, and I found the two channels have different DC offsets, so I want to use the function: calibration_coefficient_write(channel, slope, offset)   to eliminate the offset, but it seem doesn't work and the DC offset hasn't changed either. I am sure I have written it because it can be read out through function：calibration_coefficient_read(channel),I understand that once the offset is written, mcc172 will automatically subtract the offset from each AD conversion result. I don't know how to do next.

in addition，I use the function: mcc172.a_in_scan_read_numpy() to read the AD_reasult,Is it related to this？

[Fausto]

Hello @Tik Sun.

Please confirm that you are using a terminator on both channel inputs and not leaving the connectors open.

Regards,

Fausto

[DAQman]

The MCC 172 electrical specifications indicate a maximum offset error of 5.1 mV can exist, and this is after a factory calibration. So, removing a few hundred microvolts may be beyond its ability. Also, the heat from the Raspberry PI can alter the board's performance, especially if it is a Raspberry PI 5. Specifications are usually determined at 25 C.

[Tik Sun]

On 7/24/2024 at 11:23 PM, Fausto said:

Hello @Tik Sun.

Please confirm that you are using a terminator on both channel inputs and not leaving the connectors open.

Regards,

Fausto

Yes, the test was conducted after I connected a 50 Ω analog load to each input channel.