100 S/s/ch, 4-Channel C Series General-Purpose Analog Input Module

The NI-9219 is designed for multi-function testing. The NI-9219 can be used to measure signals from various sensors (such as strain gauges, resistance temperature detectors (RTDs), thermocouples, load cells, and other active sensors), as well as perform quarter-bridge, half-bridge, and full-bridge current measurements, and features built-in voltage and current excitation. You can select different measurement types independently on each channel.

III. Product Applications

The XM-USB-4431 is a data acquisition card based on the USB 2.0 bus, which can be directly connected to a computer's USB port, forming data acquisition, waveform analysis, and processing systems for various fields such as laboratories and product quality inspection centers. It can also form industrial production process monitoring systems. Its main application scenarios are:  Sound/Vibration Signal Acquisition and Analysis  Electronic Product Quality Inspection  Medical Testing  High-Precision Synchronous Signal Acquisition  I/O Control

IV. Performance Features

 A/D Converter: 24-bit Σ-Δ ADC: AD7765 (optional support for AD7764 with 312 KSPS)  Low intrinsic noise, high channel isolation;  Differential input range: ±10V;  Independent programmable gain, 4 adjustable levels: 1x, 10x, 100x, and 1000x;  AD Trigger Modes: Software timed trigger, external trigger;  Supports pre-trigger, with a maximum pre-acquisition of 2K points;  IEPE Constant Current Source: 4.38mA @2% (the board may require an external 5V power supply, depending on the USB port's power capability);  IEPE Sensor Excitation Voltage: 15V or 24V;  Constant Current Source Output Impedance: >250 kΩ at 1kHz;  Constant Current Source Noise: <500 pA/√Hz;  Coupling Mode: AC/DC;  AC Coupling -3dB Cutoff Frequency: 0.53Hz;  Analog input signal with TVS clamp protection function;  Sampling frequency can be set by software (range: 1.95KHz～156.25KHz);  Onboard large-capacity memory (4M words), supports continuous acquisition for real-time monitoring;  Onboard EEPROM, users can write custom parameters;  Board ID recognition (0～15), supports multi-card operation;  8-channel DI/DO; outputs with latch function, automatically cleared upon power-on;  Provides drivers and dynamic link libraries for WIN7/VISTA/2000/XP;  Dimensions (excluding casing): 91(W) × 139(L) (mm);

V. Technical Parameters

·Operating Voltage: 5V±0.25V ·Operating Temperature: 0℃～70℃ ·Storage Temperature: -10℃～85℃ ·Humidity: 5%～95%

VI. Working Principle

6.1, Logic Diagram

6.2, Brief Description of Working Principle The XM-USB-4431 consists of the following functional modules: USB 2.0 bus bridge circuit, address decoding and data latch, AD conversion, data storage, and other functions. Address Decoding and Data Latch: Controlled by a Field-Programmable Gate Array (FPGA) chip. Since it uses the USB 2.0 bus, users do not need to worry about specific I/O addresses; they can directly call the dynamic link library provided by our company. In 8-bit data mode, the specific I/O addresses are interpreted by the USB master control chip. AD Conversion: External analog signals are input via SMB0..SMB3, pass through 4 levels of programmable gain, enter the ADC, and the AD control timing is completed by the FPGA. Data Storage: The results of AD conversion are stored in SDRAM. The timing for reading and writing data is controlled by the FPGA. Digital I/O: 8 channels of digital input, 8 channels of digital output. Outputs have a latch function and are automatically cleared upon power-on. Frequency Measurement Principle: Measures the interval between two adjacent rising edges of a signal (square wave). For example: software sends a measurement command, and the interval between two adjacent rising edges of the signal under test is measured using a 4MHz system clock. The interval is expressed in system clock cycles, allowing users to easily calculate the signal's frequency. Since the maximum interval is represented by 24-bit data (maximum 0xFFFFFF, i.e., 16,777,215), the maximum timing duration is 4.19S (16,777,215 * 0.25 µs ≈ 4.194303S).

Note: When the START signal is low, the software initiates a frequency measurement, measuring the time width between two adjacent rising edges of the signal under test (which is 5 system clock cycles, with a 4MHz system clock). In the diagram, the TimerOver signal: 1 indicates frequency measurement is not finished; 0 indicates frequency measurement is finished. The frequency of the external signal is calculated as Fre = 4 × 10^3 ÷ (XCounter), in KHz.