NI-DAQmx Python to control NI 6281 filter

[larctique]

Hi. I have a USB 6281 and a PXI 6281. I notice that they seem to have a 40kHz filter. I wonder how to turn on and use the filter in Python properly. The goal is to reduce the noise level in my data acquisition project with as little distortion as possible, i.e. no phase shifts, offsets, or magnitude changes.

[ZYOng · Accepted solution]

with nidaqmx.Task() as task:

    channel = task.ai_channels.add_ai_voltage_chan("Dev2/ai0")

    channel.ai_lowpass_enable = 1

Reference: https://nidaqmx-python.readthedocs.io/en/latest/ai_channel.html?highlight=lowpass#nidaqmx._task_modu...

[larctique]

Thank you.

If I'm using multiple input channels, should I set channel.ai_lowpass_enable = 1 for each channel or this is a global setting?

[ZYOng · Accepted solution]

You must enable the low pass filter on all channels, otherwise an error is thrown.

nidaqmx.errors.DaqError: Property must have the same value for all channels on this device.
Property: DAQmx_AI_Lowpass_Enable
Corresponding Value: 0
Channel Name: Dev2/ai1

Task Name: _unnamedTask<0>

Status Code: -200106

You can use NI-DAQmx Syntax for Specifying Physical Channel Strings to add multiple channels in a single API call.