NI PXI Digitizers

NI PXI digitizers convert analog waveforms into digital samples for automated measurement, analysis, and recording. Installed in a compatible PXI chassis, these modular instruments combine signal conditioning, analog-to-digital conversion, onboard acquisition memory, and hardware triggering. They support applications such as transient capture, electronic component characterization, communications testing, and synchronized laboratory measurements. Unlike a standalone bench instrument, a PXI digitizer relies on a controller and software for operation, visualization, and data processing.

NI's 51xx family includes models optimized for different combinations of speed, resolution, and channel density. The two-channel PXI-5122 provides 14-bit resolution, a maximum sampling rate of 100 MS/s, and 100 MHz analog bandwidth. Example ordering number 778756-01 identifies an 8 MB-per-channel configuration. The two-channel PXI-5124 offers 12-bit resolution, sampling up to 200 MS/s, and 150 MHz bandwidth; part number 778757-01 also provides 8 MB per channel. These specifications describe different capabilities, so analog bandwidth should not be interpreted as an alias-free frequency range at every sample rate.

For higher channel counts, the PXI-5105 provides eight simultaneously sampled channels, 12-bit resolution, sampling up to 60 MS/s, and 60 MHz bandwidth. Part number 779685-01 identifies its 16 MB onboard-memory version. For precision measurements, the PXI-5922 uses flexible-resolution technology: it delivers 24-bit resolution at sampling rates up to 500 kS/s, trading resolution for speed to reach 15 MS/s at 16 bits. Part number 779153-01 identifies an 8 MB-per-channel version. This model is particularly useful for audio, spectral analysis, and low-level signal measurements.

Software is central to the platform. NI-SCOPE provides instrument control, acquisition configuration, waveform retrieval, and measurement functions for supported digitizers. Engineers can integrate acquisitions into LabVIEW or other supported programming environments. On compatible hardware, NI-TClk coordinates sample clocks and triggers across multiple instruments, helping correlate measurements without depending on software command timing.

Selection should consider input voltage range, impedance, coupling, noise performance, trigger requirements, channel count, and record length. Sampling rate determines how frequently the signal is measured, while resolution determines the number of available amplitude codes. Neither specification alone guarantees measurement accuracy; noise, distortion, and the analog front end also matter. Memory capacity affects how much waveform data can be retained locally, while sustained recording also depends on the chassis bus, controller, storage, and acquisition configuration. Verify probe and cable suitability, and check the exact module's input limits before connecting a signal.

For legacy systems, match the complete ordering number rather than the model name alone. Memory options, chassis compatibility, driver versions, and calibration requirements can affect replacement suitability. PXI and PXI Express modules are not interchangeable in every slot. Contact Apex Waves with your existing model, part number, chassis, and application requirements to discuss replacement digitizers and maintain continuity in established test systems.