National Instruments NI-9470 C Series Digital Output Module

The National Instruments NI-9470 (Part Numbers: 787089-02, 787089-01) is an industrial-grade, multipurpose digital output module with eight output channels that can handle signals ranging from 5V to 30V. Current readback, dither control, pulse width modulation (PWM), and proportional valve drive control are some of its primary characteristics. Every channel possesses a separate PWM engine, PID controller, and SAR ADC.

Transient overvoltage protection and crimp terminal interface make the NI-9470 a dependable and safe device. In measurement applications, it improves safety by offering channel-to-earth ground isolation. For reliable diagnostics, the module provides overcurrent, overtemperature, power supply failure, and power supply voltage readback detection.

There are two output modes available: Average Current mode for closed-loop control utilizing an inbuilt PID controller and Duty Cycle mode for open-loop control. Channels are in a tristate state when they first turn on, and PWM output happens once the software operation starts. Channel closure is the outcome of fault conditions.

The master timebase, which has an internal frequency of 12.8 MHz, regulates the data rate, PWM, and dither frequencies of the module. For multi-module installations, external timebase synchronization is supported. To improve noise rejection, a hardware digital comb filter averages current ADC samples.

For the purpose of measuring current, each channel has low-side sensing resistors. The number of active channels determines the maximum current rating, with a peak current restriction of 3.5A per channel. PWM frequency precision is as high as 2.048 kHz.

PID controller and dither engine of NI-9470 provide fine control over output parameters, with channel-specific settings. By producing a triangular wave with a zero DC average, the dither engine improves output stability.