NI PXI-6704 Overview
The National Instruments PXI-6704 is a 16-bit, 32-channel PXI Analog Output Module. It's built for creating software-timed voltage and current output applications, allowing users to independently set the output range for each channel. It also integrates eight 5 V TTL/CMOS digital I/O lines, enhancing its versatility for various control and stimulus tasks within a PXI system.
Product Detailed Description
Functionality: The PXI-6704's primary role is to generate stable and precise analog voltage and current outputs. It's ideal for providing setpoints, simulating sensors, driving actuators, or performing open-loop control in automated systems.
Architecture: It features a single 16-bit Digital-to-Analog Converter (DAC) that is time-division multiplexed across all output channels. Each channel incorporates a track-and-hold circuit to maintain its output value between DAC updates, ensuring stable and consistent signals.
Output Channels:
16 Voltage Outputs: These channels can independently output a voltage in the range of -10.1 V to +10.1 V.
16 Current Outputs: These channels can independently source current in the range of 0.1 mA to 20.2 mA. They operate as current sources and do not require an external excitation source.
The design allows for both voltage and current outputs to be used simultaneously.
Digital I/O: Includes 8 digital I/O lines (5 V TTL/CMOS compatible) for simple control, status monitoring, or triggering.
Calibration: The module features persistent self-calibration, and its design ensures excellent channel-to-channel matching of offset and gain errors, which helps in maintaining high accuracy across all outputs. An onboard temperature sensor monitors the air temperature over the board, near the precision voltage reference, to compensate for temperature drift.
Connectivity: It connects to external circuitry via a 68-pin male I/O connector. Companion terminal blocks (like TBX-68, SCB-68A, CB-68LPR, CB-68LP) are available for easy and secure wiring.
Software Integration: It's designed to work seamlessly with NI's software environment, primarily NI-DAQmx drivers, LabVIEW, LabWindows/CVI, Measurement Studio, and other compatible programming languages (e.g., Visual Studio .NET, Visual Basic, C/C++, C#).
Product Parameters
(Note: Specific values are typical and may have slight variations. Always refer to the official NI PXI-6704 user manual and specifications document for the most accurate and up-to-date information.)
Analog Output Channels: 32 total (16 voltage, 16 current)
Analog Output Resolution: 16 bits
Maximum Update Rate: Static (software-timed)
Analog Output Voltage Range: -10.1 V to +10.1 V
Analog Output Current Range: 0.1 mA to 20.2 mA
Digital I/O Lines: 8 (5 V TTL/CMOS)
Bus Connector: PXI Hybrid (compatible with PXI and PXI Express hybrid slots)
I/O Connector: 68-pin male SCSI-type
Power Consumption: (Refer to datasheet for exact values, typically low as it's a static output device)
Operating Temperature: 0 °C to +55 °C
Storage Temperature: -20 °C to +70 °C
Humidity: 5% to 90% RH, non-condensing
Altitude: Up to 2,000 m
Dimensions: Approximately 6.3 x 3.9 inches (PXI 3U module standard width)
Weight: Approximately 0.7 kg (1.5 lbs)
Certification: CE, cULus, etc. (refer to product certification documents)
Recommended Warm-up Time: 15 minutes for specified accuracy.
Product Advantages
High Channel Count: With 32 analog output channels (16 voltage, 16 current) in a single PXI slot, it offers high density for complex test and control systems.
Flexible Output Types: The ability to generate both voltage and current outputs from one module increases versatility and reduces the need for multiple specialized modules.
High Resolution and Accuracy: 16-bit resolution and specified absolute accuracy ensure precise control and stimulus generation.
Integrated Digital I/O: The 8 digital lines add basic control and synchronization capabilities, making the module more self-contained for certain applications.
PXI Platform Benefits: Leverages the advantages of the PXI platform, including compact size, ruggedness, integrated timing and synchronization (when combined with a PXI chassis), and strong software integration with LabVIEW and other NI tools.
Software-Timed Control: Ideal for applications requiring stable, static outputs for control loops, sensor simulation, or setpoint generation.
Self-Calibration: Persistent self-calibration helps maintain accuracy over time and temperature variations, reducing manual calibration needs.
Precautions
Static Output Device: The PXI-6704 is a static output device; it's not designed for high-speed, continuous waveform generation. For dynamic, high-frequency signals, dedicated arbitrary waveform generators or dynamic analog output modules would be more appropriate.
Wiring and Connectivity: Use appropriate shielded cables and terminal blocks (like NI's CB-68LP series) to ensure signal integrity and reduce noise. Incorrect wiring can lead to inaccurate outputs or damage.
Power-On States: Understand and configure the power-on states of the outputs to prevent unexpected behavior when the system powers up.
Environmental Conditions: Operate the module within its specified temperature and humidity ranges. Excessive heat or moisture can affect performance and longevity.
Calibration: While it performs self-calibration, periodic external calibration by a certified lab is recommended for applications requiring high, traceable accuracy.
Software Compatibility: Ensure your NI-DAQmx driver version and application development environment (e.g., LabVIEW) are compatible with the PXI-6704.
ESD Protection: Always handle PXI modules with proper electrostatic discharge (ESD) precautions to prevent damage to sensitive components.
Load Considerations: Ensure the connected load's impedance is within the module's driving capabilities for both voltage and current outputs.
Product Applications
The NI PXI-6704 is well-suited for a variety of applications requiring precise and stable analog outputs in a modular test and measurement environment:
Automated Test Equipment (ATE):
Generating stimulus signals for component testing (e.g., sensors, actuators).
Providing control voltages/currents for automated calibration routines.
Simulating sensor outputs for system validation.
Process Control and Automation:
Providing setpoints to PID controllers or other control loops.
Controlling valves, motors, and other actuators in industrial processes.
Simulating process variables for control system validation and tuning.
Hardware-in-the-Loop (HIL) Simulation:
Generating simulated sensor signals or control inputs to test embedded controllers.
Creating closed-loop test environments for automotive, aerospace, or industrial control units.
Scientific Research and Education:
Driving experimental setups that require precise voltage or current sources.
Creating configurable stimulus for various physical phenomena.
Laboratory exercises involving basic control theory and signal generation.
Power Supply Control:
Sensor/Signal Simulation:
