PCI-MXI-2 插入式電路板 可保存模型上電時(shí)加載的默認(rèn)寄存器值
NI PCI-MXI-2(部件號(hào)：777185-01、182685K-01)是NIMXI-2系列的一部分。該電路板可以插入用戶基于 PCI 的計(jì)算機(jī)上的擴(kuò)展插槽中。 PCI-MXI-2 將用戶的基于 PCI 的計(jì)算機(jī)直接連接到 MXIbus，反之亦然。由于 PCI-MXI-2 使用與其他基于 VXIbus 消息的儀器相同的通信寄存器集，因此其他 MXIbus 儀器將 PCI-MXI-2 視為 VXIbus 儀器。該插入式電路板支持 D64、塊和同步 MXI 周期，可實(shí)現(xiàn)高性能信息傳輸，支持 MXI 總線終端，并符合 PCI 規(guī)范 2.0 和 MXIbus 規(guī)范 2.0。該器件的可編程存儲(chǔ)器空間最小為 32 kb，數(shù)據(jù)路徑為 32 位。
NI PCI-MXI-2 插 插 式 電路 板 具有 板載 EEPROM， 可 保存 模型 上 電 時(shí) 加載 的 默認(rèn) 寄存器 值。EEPROM有兩個(gè)部分：出廠配置部分和用戶配置部分。模型的出廠配置部分保存了默認(rèn)用戶設(shè)置的備份，而用戶配置的部分可以更改。出廠配置是最低配置，即使修改了用戶配置，用戶仍可以啟動(dòng)PCI-MXI-2。更改設(shè)置時(shí)，請(qǐng)勿修改 U3 開關(guān) 4 和 17 的設(shè)置。
PCI-MXI-2使用NI-VXI/NI-VISA軟件運(yùn)行，并與LabVIEW、LabWindows/CVI和Measurement Studio等軟件包兼容。該設(shè)備可以使用Measurement & Automation Explorer (MAX)工具進(jìn)行配置。
PCI-MXI-2是一款PCI-MXI模塊，可以采集模擬量輸入信號(hào)，通過(guò)PCI總線實(shí)時(shí)傳輸?shù)接?jì)算機(jī)中，用于數(shù)據(jù)采集、信號(hào)處理、測(cè)試控制等領(lǐng)域。
模擬量輸入信號(hào)是指連續(xù)的電壓、電流、壓力、溫度等可變物理量，通過(guò)模擬信號(hào)輸入模塊(如PCI-MXI-2模塊)轉(zhuǎn)換成計(jì)算機(jī)能夠識(shí)別的數(shù)字信號(hào)。
模擬信號(hào)轉(zhuǎn)化為數(shù)字信號(hào)需要經(jīng)過(guò)三個(gè)步驟：
采樣：NI PCI-MXI-2(模擬信號(hào)被采樣成一系列的離散樣本，完成時(shí)間離散化，但在幅度上還是連續(xù)的。
量化：將采樣得到的模擬信號(hào)幅值轉(zhuǎn)換成數(shù)字量，也就是將連續(xù)的模擬信號(hào)離散化成一系列的數(shù)字值，這時(shí)信號(hào)不僅在時(shí)間上不再連續(xù)，在幅度上也不連續(xù)了。
編碼：NI PCI-MXI-2(將量化后的模擬信號(hào)數(shù)字化成二進(jìn)制編碼，雖然在量化之后信號(hào)已經(jīng)變成了數(shù)字信號(hào)，但二進(jìn)制字的表示方法有很多，還要根據(jù)精度、動(dòng)態(tài)范圍及實(shí)現(xiàn)成本等多個(gè)角度選擇所需的二進(jìn)制編碼方式。
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.
