MVI56-MCM  主站/从站通信模块  具备两个可独立配置的串行端口

Modbus 主站/从站通信模块

MVI56E-MCM/MCMXT

使用 MVI56E 增强型 Modbus 主站/从站通信模块，罗克韦尔自动化® ControlLogix® 处理器可以轻松连接采用 RTU/ASCII 串行通信协议的设备。

MVI56E-MCM 和 MVI56E-MCMXT 作为 ControlLogix 背板上的输入/输出模块，使得 Modbus 数据对于处理器来说就像是 I/O 数据。与处理器进行的数据传输与 Modbus 网络上的通信异步。模块具备两个可独立配置的串行端口，可运行在相同或不同的 Modbus 网络中。每个端口都可配置为 Modbus 主站或从站，共享同一个由用户控制的 10000 字数据库。

两个模块在功能上完全相同。MVI56E-MCM 用于标准过程应用项目。MVI56E-MCMXT 用于 Logix-XT™ 控制平台，可工作在极端环境中。它能耐受更高的工作温度，并且具备在严苛或腐蚀条件下提供保护的敷形涂层。

MVI56-MCM 主站/从站通信模块是一种通信系统中的模块，用于实现主站和从站之间的数据传输和控制。主站通常是通信系统中的控制中心，负责发送控制指令和数据给从站，并接收从站反馈的数据。从站则负责执行主站的指令，并把采集的数据发送回主站。

在主站/从站通信模块中，主站和从站之间的通信协议是关键。协议数据单元（PDU）是通信协议的核心部分，它定义了PDU的格式、协议使用的各种数据概念、如何使用功能代码访问数据，以及每个功能代码的具体实现和限制。

在Modbus应用协议规范中，PDU的格式被定义为一个功能代码，后面跟着一组关联的数据。数据的大小和内容由功能代码定义，整个PDU（功能代码和数据）的大小不能超过253个字节。每个功能代码都有一个特定的行为，设备可以根据所需的应用程序行为灵活地实现这些行为。

总之，MVI56-MCM 主站/从站通信模块是一种实现主站和从站之间数据传输和控制的通信系统模块，它遵循一定的通信协议规范，其中PDU是协议的核心部分。在实际应用中，根据具体需求和协议规范，可以选择不同的功能代码来实现所需的行为。

MVI56-MCM  主站/从站通信模块  具备两个可独立配置的串行端口

Modbus master/slave communication module

MVI56E-MCM/MCMXT

With the MVI56E Enhanced Modbus master/Slave communication module, Rockwell Automation ® ControlLogix® processors can easily connect devices using the RTU/ASCII serial communication protocol.

The MVI56E-MCM and MVI56E-MCMXT act as input/output modules on the ControlLogix backplane, making Modbus data look like I/O data to the processor. The data transfer with the processor is asynchronous with the communication on the Modbus network. The module has two independently configurable serial ports that can operate in the same or different Modbus networks. Each port can be configured as a Modbus master or slave, sharing the same user-controlled 10,000-word database.

The two modules are functionally identical. The MVI56E-MCM is used for standard process application projects. The MVI56E-MCMXT is used in the Logix-XT™ control platform to operate in extreme environments. It withstands higher operating temperatures and has a form coating that provides protection under harsh or corrosive conditions.

The MVI56-MCM master/slave station communication module is a module in a communication system that implements data transmission and control between the master and slave stations. The master station is usually the control center in the communication system, responsible for sending control instructions and data to the slave station, and receiving the feedback data from the slave station. The slave station is responsible for executing the command of the master station and sending the collected data back to the master station.

In the master/slave communication module, the communication protocol between master and slave is the key. The protocol data Unit (PDU) is the core part of the communication protocol, which defines the format of the PDU, the various data concepts used by the protocol, how to use the function code to access the data, and the specific implementation and restrictions of each function code.

In the Modbus application protocol specification, the format of a PDU is defined as a functional code followed by a set of associated data. The size and content of the data are defined by the function code, and the size of the entire PDU (function code and data) cannot exceed 253 bytes. Each feature code has a specific behavior that the device has the flexibility to implement based on the desired application behavior.

In short, MVI56-MCM master/slave station communication module is a communication system module that realizes data transmission and control between master and slave station. It follows certain communication protocol specifications, and PDU is the core part of the protocol. In practical applications, according to specific requirements and protocol specifications, different functional codes can be selected to achieve the desired behavior.