Product Overview
The National Instruments PCIe-6351 is a multifunction data acquisition card for PCI Express computers. It belongs to the NI X Series family and provides 16 analog input channels with 16 bit resolution and a maximum single channel sampling rate of 1.25 MS/s. The card also includes two analog output channels, 24 digital input and output lines, and four counters.
The PCIe-6351 is designed for automated test, laboratory measurement, production verification, and control applications that need fast acquisition and mixed signal capability in a desktop computer. The PCI Express interface provides high bandwidth to the host, which supports continuous streaming and waveform generation.
High Speed Analog Input
The analog input section provides 16 channels with 16 bit resolution and a maximum single channel rate of 1.25 MS/s, with the aggregate rate shared across active channels. Selectable input ranges, including plus or minus 10 V, plus or minus 5 V, and plus or minus 1 V, allow the card to match different signal levels for effective use of the available resolution.
Hardware timed acquisition, external sample clocks, and analog and digital triggering support repeatable measurement sequences. 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.
Analog Output and Digital I/O
The card includes two 16 bit analog output channels for control voltages, setpoints, and waveform generation. Hardware timed output produces deterministic waveform sequences, which is useful for stimulus response testing, actuator command profiles, and calibration signals. Engineers should confirm the load and settling requirements of the driven device.
Twenty four digital lines provide logic level control, relay driving through external conditioning, and status monitoring. Four 32 bit counters support event counting, frequency measurement, pulse generation, and encoder position tracking. Because analog and digital tasks can share timing signals, the card can implement coordinated mixed signal sequences within one application.
Timing and Synchronization
NI-DAQmx provides start triggers, reference triggers, pause triggers, and sample clock configuration for the PCIe-6351. These features allow acquisition and generation to be aligned with external events or with other DAQ devices. Counter outputs can be routed as triggers, and analog or digital events can gate tasks.
For larger systems, multiple cards can be synchronized using shared timing and trigger signals where supported. Channel expansion must be planned so that sample clocks remain consistent across devices. Documenting clock sources, trigger routes, and channel mapping helps maintain reproducibility when the system is duplicated.
Software and Accessories
The PCIe-6351 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. Screw terminal, spring terminal, and mass termination accessories are available for different wiring needs.
Installation requires a PCI Express slot with adequate airflow and a host within the supported operating specifications. Cables should be routed away from power switching equipment, and shields should be terminated according to the accessory documentation. Regular verification of calibration and channel function supports long term measurement confidence.
Typical Applications
High speed analog data acquisition
Waveform generation and stimulus response test
Mixed signal automated test systems
Encoder position and frequency measurement
Laboratory measurement and prototype validation
PCI Express based test and control systems
The PCIe-6351 provides 16 analog inputs, 1.25 MS/s sampling, 2 analog outputs, 24 digital lines, and 4 counters in an X Series PCI Express card. Its speed, timing features, and NI-DAQmx support make it a practical platform for combined measurement and control tasks.
