MCC 128 Noise

[meatball.papi]

Hi all,

I am using the MCC 128 hooked up to a Raspberry Pi 4B 8GB. I have noticed that there is a fair bit of noise when reading the signals from the sensors with nothing plugged in, more than seems to be from the sensor. I've attached a screenshot of running the web_server.py from the daqhats/examples/python/mcc128/web_server from the daqhats GitHub repository. It seems as though this noise is fluctuating at around 50-60 Hz. As far as I can tell it isn't related to the temperature the Pi has been plugged in; this kind of behavior has been observed both when the Pi has been plugged in for a long time as well as when it has been plugged in for several hours.

If it helps at all, I'm running the web_server.py with its default settings; everything that I'm changing is from the web server GUI.

I have also tried using the Pi's on board GPIO pins to have the MCC128 read the 5V difference, which did come out correct (one channel was at 0V and another at 5V), however the sensor we are trying to use with the MCC128 (ULPSM-O3 968-046 ozone sensor) has a range of 0-3V, with +/- 3mV precision ideal.

Any recommendations on how to fix this would be much appreciated!

Thanks!

Josh

[Fausto]

Hello @meatball.papi.

What you have experienced is normal for open channels.  If a channel is enabled, then it must have a connected sensor.  Disable any channels without a sensor.

Regards,

Fausto

[meatball.papi]

Hi Fausto,

 

I've attached a screenshot from data that only has channels that are measuring the voltage of our O3 sensor that I mentioned earlier. This is with the sensor measuring no ozone, and we have been seeing that there is an excessive amount of noise from the DAQ. Any thoughts on this one?

 

Josh

[Fausto]

Hello @meatball.papi.

Are all three signals from one O3 sensor or multiple sensors?

Are the input signals wired to the MCC 128 in single-ended or differential input mode?

Disconnect all signal wires and reconnect one signal to analog input channel 0 in differential mode.  Test each signal individually on channel 0.

Do the measurements reflect expected readings?

Regards,

Fausto