Product Overview
The National Instruments PXI-6225 is a multifunction data acquisition module for PXI systems. It belongs to the NI M Series DAQ family and provides 80 analog input channels, 16 bit resolution, two analog output channels, 24 digital input and output lines, and two counters. The module is designed for high channel count measurement in automated test, laboratory monitoring, and industrial data logging.
Because the PXI-6225 is a PXI module, it shares the chassis power, cooling, and timing resources with other instruments. This allows a single PXI system to combine high channel count analog input with switching, signal generation, and measurement instruments in one application. The module is suited to systems that monitor many sensors or voltage points and need a compact, integrated solution.
High Channel Count Analog Input
Eighty analog input channels allow the module to monitor a large number of sensors, transducers, and voltage points without adding multiple DAQ devices. The 16 bit resolution provides fine measurement steps across the selected input range. Engineers should confirm the per channel sampling rate for the planned scan list, because the aggregate rate is shared across active channels.
The analog input system supports hardware timed acquisition, external sample clocks, and triggering. Multichannel scanning can be configured for single ended or differential connections depending on the accessory and wiring. Differential wiring is often preferred for low level signals and for rejecting common mode noise in industrial environments.
Analog Output and Digital I/O
The module includes two analog output channels for control voltages, setpoints, and simple waveforms. Hardware timed output supports repeatable sequences, which is useful for stimulus response testing and control loop validation. Engineers should verify the load and settling requirements of the connected device before using the outputs in a closed loop.
Twenty four digital lines provide logic level control, relay driving through external conditioning, and status monitoring. Two 32 bit counters support event counting, frequency measurement, pulse generation, and encoder position tracking. The combination of analog and digital functions allows the module to handle mixed signal tasks within a single PXI slot.
Timing and Synchronization
NI-DAQmx exposes start triggers, reference triggers, pause triggers, and sample clock configuration for the PXI-6225. These features allow acquisition and generation to be aligned with external events or with other PXI modules. Counter outputs can trigger analog operations, and digital events can gate acquisition tasks.
Within a PXI chassis, the module can be synchronized with switches, digitizers, and signal generators through the backplane trigger lines. This supports test sequences that route signals, apply stimuli, capture responses, and evaluate results in a defined order. Documenting the trigger routing and clock source helps ensure reproducibility across stations.
Software and Accessories
The PXI-6225 is supported by NI-DAQmx and can be programmed with LabVIEW, LabWindows/CVI, Measurement Studio, and other NI-DAQmx compatible environments. The driver handles channel configuration, scaling, calibration metadata, and task management. Signal conditioning accessories and shielded cables are available for sensor connection and noise reduction.
Wiring practice affects measurement quality. Shielded cable, separation from power switching conductors, and a defined ground architecture improve results in electrically noisy environments. Engineers should verify channel function and calibration periodically to maintain confidence in long term measurements.
Typical Applications
High channel count analog data acquisition
Sensor monitoring and laboratory data logging
Mixed signal automated test systems
Control voltage generation and stimulus
Event counting and frequency measurement
PXI based test racks with many measurement points
The PXI-6225 provides 80 analog inputs, 16 bit resolution, analog outputs, digital I/O, and counters in an M Series PXI module. Its channel density and NI-DAQmx support make it suitable for high channel count measurement and control applications.
