PCI-MXI-2  插入式电路板  可保存模型上电时加载的默认寄存器值

National Instruments PCI-MXI-2插入式电路板

NI PCI-MXI-2（部件号：777185-01、182685K-01）是NIMXI-2系列的一部分。该电路板可以插入用户基于 PCI 的计算机上的扩展插槽中。 PCI-MXI-2 将用户的基于 PCI 的计算机直接连接到 MXIbus，反之亦然。由于 PCI-MXI-2 使用与其他基于 VXIbus 消息的仪器相同的通信寄存器集，因此其他 MXIbus 仪器将 PCI-MXI-2 视为 VXIbus 仪器。该插入式电路板支持 D64、块和同步 MXI 周期，可实现高性能信息传输，支持 MXI 总线终端，并符合 PCI 规范 2.0 和 MXIbus 规范 2.0。该器件的可编程存储器空间最小为 32 kb，数据路径为 32 位。

NI PCI-MXI-2 插 插 式 电路 板 具有 板载 EEPROM， 可 保存 模型 上 电 时 加载 的 默认 寄存器 值。EEPROM有两个部分：出厂配置部分和用户配置部分。模型的出厂配置部分保存了默认用户设置的备份，而用户配置的部分可以更改。出厂配置是最低配置，即使修改了用户配置，用户仍可以启动PCI-MXI-2。更改设置时，请勿修改 U3 开关 4 和 17 的设置。

PCI-MXI-2使用NI-VXI/NI-VISA软件运行，并与LabVIEW、LabWindows/CVI和Measurement Studio等软件包兼容。该设备可以使用Measurement & Automation Explorer （MAX）工具进行配置。

PCI-MXI-2是一款PCI-MXI模块，可以采集模拟量输入信号，通过PCI总线实时传输到计算机中，用于数据采集、信号处理、测试控制等领域。

模拟量输入信号是指连续的电压、电流、压力、温度等可变物理量，通过模拟信号输入模块（如PCI-MXI-2模块）转换成计算机能够识别的数字信号。

模拟信号转化为数字信号需要经过三个步骤：

采样：NI PCI-MXI-2（模拟信号被采样成一系列的离散样本，完成时间离散化，但在幅度上还是连续的。

量化：将采样得到的模拟信号幅值转换成数字量，也就是将连续的模拟信号离散化成一系列的数字值，这时信号不仅在时间上不再连续，在幅度上也不连续了。

编码：NI PCI-MXI-2（将量化后的模拟信号数字化成二进制编码，虽然在量化之后信号已经变成了数字信号，但二进制字的表示方法有很多，还要根据精度、动态范围及实现成本等多个角度选择所需的二进制编码方式。

PCI-MXI-2  插入式电路板  可保存模型上电时加载的默认寄存器值

National Instruments PCI-MXI-2 Plug-in circuit board

The NI PCI-MXI-2 (part number: 777185-01, 182685K-01) is part of the NIMXI-2 series. The board can be plugged into an expansion slot on the user's PCI-based computer. PCI-MXI-2 connects the user's PCI-based computer directly to MXIbus and vice versa. Because PCI-MXI-2 uses the same communication register set as other VXIbus message-based instruments, other MXIbus instruments treat PCI-MXI-2 as a VXIbus instrument. The plug-in board supports D64, block, and synchronous MXI cycles for high-performance information transfer, supports MXIbus terminals, and complies with PCI specification 2.0 and MXIbus specification 2.0. The device has a minimum of 32 kb of programmable memory space and a 32-bit data path.

The NI PCI-MXI-2 plug-in circuit board has an onboard EEPROM that saves the default register values loaded when the model is powered on. The EEPROM has two parts: the factory configuration part and the user configuration part. The factory configuration part of the model keeps a backup of the default user Settings, while the user configuration part can be changed. The factory configuration is the minimum configuration, and the user can start PCI-MXI-2 even if the user configuration is modified. When changing the Settings, do not modify the Settings of U3 switches 4 and 17.

PCI-MXI-2 runs with NI-VXI/NI-VISA software and is compatible with packages such as LabVIEW, LabWindows/CVI, and Measurement Studio. The device can be configured using the Measurement & Automation Explorer (MAX) tool.

Pci-mxi-2 is a PCI-MXI module, which can collect analog input signals and transmit them to the computer in real time through PCI bus for data acquisition, signal processing, test control and other fields.

Analog input signal refers to the continuous voltage, current, pressure, temperature and other variable physical quantities, through the analog signal input module (such as PCI-MXI-2 module) converted into a digital signal that can be recognized by the computer.

Converting an analog signal to a digital signal requires three steps:

Sampling: NI PCI-MXI-2 (Analog signal is sampled into a series of discrete samples, complete time discretization, but still continuous in amplitude.

Quantization: The analog signal amplitude obtained by sampling is converted into a digital quantity, that is, the continuous analog signal is discretized into a series of digital values, then the signal is not only no longer continuous in time, but also discontinuous in amplitude.

Coding: NI PCI-MXI-2 (the analog signal after quantization is digitized into binary coding, although the signal has become a digital signal after quantization, but there are many ways to represent binary words, but also according to the accuracy, dynamic range and implementation cost and other angles to choose the required binary coding method.