FlexTalk Modbus Master C++ 库指南

2星需积分: 9 46 浏览量更新于2024-08-01 收藏 759KB PDF 举报

"FlexTalk Modbus Master C++ Library 是一个专用于实现Modbus通信协议的C++库，适用于多种操作系统平台，包括Windows、ucLinux、arm-linux交叉编译工具链、QNX4和VxWorks。该库的主要功能是允许开发者在他们的应用程序中集成Modbus主设备功能，支持串行和MODBUS/TCP协议。手册详细介绍了安装、编译、链接过程以及如何在应用中使用Modbus协议，并提供了相关背景和技术信息。" 本文将详细讨论FlexTalk Modbus Master C++ Library的相关知识点。 1. **Modbus协议**：Modbus是一种广泛使用的工业通信协议，它定义了数据在控制器（主设备）和远程设备（从设备）之间交换的格式。这个C++库专注于实现Modbus主设备功能，使开发者能够控制支持Modbus的设备。 2. **Library Structure**：FlexTalk Modbus Master C++ Library的结构包含一系列类和函数，用于处理Modbus通信的不同方面，如建立连接、发送请求和接收响应。库的设计可能包括主设备类、协议处理类和错误处理机制。 3. **安装与源码编译**：对于不同的操作系统，安装步骤和编译源码的方法有所不同。例如，在Windows系统上，用户需要解压并编译源代码；而对于ucLinux、arm-linux、QNX4和VxWorks等嵌入式系统，可能需要使用特定的交叉编译工具链进行编译。 4. **链接应用**：在Linux、UNIX和QNX系统上，开发者需要编译应用并与库链接，以确保应用能使用库提供的功能。Windows系统也有相应的编译和链接过程。 5. **协议集成**：库提供两种主要的协议使用方式——串行协议和MODBUS/TCP协议。串行协议包括ASCII和RTU模式，而MODBUS/TCP协议则适用于网络通信。开发者需要了解这些协议的差异以及如何在应用中正确使用它们。 6. **Modbus背景和技术信息**：文档详细介绍了Modbus的历史和技术细节，包括协议功能、从设备标识、寄存器模型和数据表、数据编码以及三种协议的具体实现方式（ASCII、RTU和TCP）。这些信息对理解库的使用至关重要。 7. **设计背景**：这部分可能涉及到库的设计原则、选择C++作为实现语言的原因以及为提高效率和可靠性所做的优化。 8. **示例代码**：手册中包含了串行通信的示例代码，帮助开发者快速理解和应用库的功能。通过这些示例，用户可以学习如何创建和管理Modbus连接，发送和接收数据。 FlexTalk Modbus Master C++ Library为开发人员提供了一个强大的工具，以便在多种平台上构建支持Modbus通信的应用程序。其详尽的文档使得开发者无论在理论知识还是实践操作上都能得到充分的指导。

FieldTalk Modbus Master C++ Library: Software manual

mbusProtocol.closeProtocol();

7. Error Handling

Serial protocol errors like slave device failures, transmission failures, checksum errors and time-outs

return an error code. The following code snippet can handle and report these errors:

int result;

result = mbusProtocol.readMultipleRegisters(1, 100, dataSetArray, 10);

if (result != FTALK_SUCCESS)

{

fprintf(stderr, "%s!\n", getBusProtocolErrorText(result));

// Stop for fatal errors

if (!(result & FTALK_BUS_PROTOCOL_ERROR_CLASS))

return;

}

An automatic retry mechanism is available and can be enabled with mbusProtocol.setRetryCnt(3)

before opening the protocol port.

Using MODBUS/TCP Protocol

Let’s assume we want to talk to a Modbus slave device with unit address 1 and IP address 10.0.0.11.

The registers for reading are in the reference range 4:00100 to 4:00119 and the registers for writing

are in the range 4:00200 to 4:00219. The discretes for reading are in the reference range 0:00010 to

0:00019 and the discretes for writing are in the range 0:00020 to 0:00029.

1. Include the library header ﬁles

#include "MbusTcpMasterProtocol.hpp"

2. Device data proﬁle deﬁnition

Deﬁne the data sets which reﬂects the slave’s data proﬁle by type and size:

short readRegSet[20];

short writeRegSet[20];

int readBitSet[10];

int writeBitSet[10];

If you are using ﬂoats instead of 16-bit shorts deﬁne:

float readFloatSet[10];

float writeFloatSet[10];

Note that because a ﬂoat occupies two 16-bit registers the array size is half the size it would be for

16-bit shorts!

If you are using 32-bit ints instead of 16-bit shorts deﬁne:

What You should know about Modbus

5 What You should know about Modbus

Some Background

The Modbus

protocol family was originally developed by Schneider Automation Inc. as an indus-

trial network for their Modicon

programmable controllers.

Since then the Modbus protocol family has been established as vendor-neutral and open communi-

cation protocols, suitable for supervision and control of automation equipment.

Technical Information

Modbus is a master/slave protocol with half-duplex transmission.

One master and up to 247 slave devices can exist per network.

The protocol deﬁnes framing and message transfer as well as data and control functions.

The protocol does not deﬁne a physical network layer. Modbus works on different physical network

layers. The ASCII and RTU protocol operate on RS-232, RS-422 and RS-485 physical networks.

The Modbus/TCP protocol operates on all physical network layers supporting TCP/IP. This com-

promises 10BASE-T and 100BASE-T LANs as well as serial PPP and SLIP network layers.

Note:

To utilise the multi-drop feature of Modbus, you need a multi-point network like RS-485. In

order to access a RS-485 network, you will need a protocol converter which automatically

switches between sending and transmitting operation. However some industrial hardware plat-

forms have an embedded RS485 line driver and support enabling and disabling of the RS485

transmitter via the RTS signal. Some FieldTalk C++ editions support this RTS driven RS485

mode.

The Protocol Functions

Modbus deﬁnes a set of data and control functions to perform data transfer, slave diagnostic and

PLC program download.

FieldTalk implements the most commonly used functions for data transfer as well as some diagnos-

tic functions. The functions to perform PLC program download and other device speciﬁc functions

are outside the scope of FieldTalk.

All Bit Access and 16 Bits Access Modbus Function Codes have been implemented. In addition the

most frequently used Diagnostics Function Codes have been implemented. This rich function set

enables a user to solve nearly every Modbus data transfer problem.

The following table lists the available Modbus Function Codes:

FieldTalk Modbus Master C++ Library: Software manual

Function Code Current Terminology Classic Terminology

Bit Access

1 Read Coils Read Coil Status

2 Read Inputs Discretes Read Input Status

5 (05 hex) Write Coil Force Single Coil

15 (0F hex) Force Multiple Coils Force Multiple Coils

16 Bits Access

3 Read Multiple Registers Read Holding Registers

4 Read Input RegistersRead Input

Registers

Read Input Registers

6 Write Single Register Preset Single Register

16 (10 Hex) Write Multiple Registers Preset Multiple Registers

22 (16 hex) Mask Write Register Mask Write Register

23 (17 hex) Read/Write Registers Read/Write Registers

Diagnostics

7 (07 hex) Read Exception Status Read Exception Status

8 sub code 00 Diagnostics - Return Query Data Diagnostics - Return Query Data

How Slave Devices are identiﬁed

A slave device is identiﬁed with its unique address identiﬁer. Valid address identiﬁers supported

are 1 to 247. Some library functions also extend the slave ID to 255, please check the individual

function’s documentation.

Some Modbus functions support broadcasting. With functions supporting broadcasting, a master

can send broadcasts to all slave devices of a network by using address identiﬁer 0. Broadcasts are

unconﬁrmed, there is no guarantee of message delivery. Therefore broadcasts should only be used

for uncritical data like time synchronisation.

The Register Model and Data Tables

The Modbus data functions are based on a register model. A register is the smallest addressable

entity with Modbus.

The register model is based on a series of tables which have distinguishing characteristics. The four

tables are:

Table Classic Terminology Modicon

Table

Characteristics

Discrete outputs Coils 0:00000 Single bit, alterable by

an application program,

read-write

Discrete inputs Inputs 1:00000 Single bit, provided by

an I/O system,

read-only

Input registers Input registers 3:00000 16-bit quantity, provided

by an I/O system,

read-only

Output registers Holding registers 4:00000 16-bit quantity, alterable

by an application

program, read-write

The Modbus protocol deﬁnes these areas very loose. The distinction between inputs and outputs

and bit-addressable and register-addressable data items does not imply any slave speciﬁc behaviour.

It is very common that slave devices implement all tables as overlapping memory area.

剩余187页未读，继续阅读

geggegeda

粉丝: 47
资源: 33

FlexTalk Modbus Master C++ 库指南

windows下最好用的modbus实现(FieldtalkModbus)

modbus master C++源代码

WSMBT Modbus Master TCP/IP Component for .NET

ModbusMaster.rar_单片机开发_Visual_C++_

ModbusMaster:启发您的 Arduino 成为 Modbus 主

esp32ModbusRTU：ESP32的Modbus RTU客户端

modbus-tcp.rar

modbuspp-master

modbusrtu主站 master库

MODBUS TCP 的C++源码

最新资源