Documentation

Coupling

Specify input coupling mode

Description

The Coupling property is visible only if the device you are using supports coupling and the value can be changed. Coupling can be DC or AC. If Coupling is DC, the input is connected directly to the amplifier. If Coupling is AC, a series capacitor is inserted between the input connector and the amplifier.

When AC coupling is selected, the DC bias component of the measured signal is filtered out of the waveform by the hardware. This is typically used with dynamic signals such as audio. When DC coupling is selected, the complete signal including the DC bias component is measured. This is typically used with slowly changing signals such as temperature or voltage readings.

Values

AC

A series capacitor is inserted between the input connector and the amplifier.

DC

The input is connected directly to the amplifier.

The default is set to AC for

  • National Instruments® devices that use the NI-DAQmx interface and support AC coupling

  • National Instruments DSA cards using the Traditional NI-DAQ interface

In all other cards, the default is set to DC.

Examples

Create a session and add an analog input channel.

s = daq.createSession('ni');
ch = addAnalogInputChannel(s,'Dev4','ai1','Voltage')

Change the coupling type to DC:

ch.Coupling = 'DC';
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