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Node-RED Tutorial Home

介绍
Node-RED编程基础
建立你的第一个流
基础节点和流
核心节点

例子:
使用Node-RED搭建一个天气预报面板
基于 SIMATIC IOT2040 的 Node-RED S7 通信

[提醒] 由于技术有限，错误在所难免，如有错误，希望您不吝赐教，指出文章错误。

Modbus

Modbus是一种串行通信协议，是Modicon公司（现在的施耐德电气 Schneider Electric）于1979年为使用可编程逻辑控制器（PLC）通信而发表。Modbus已经成为工业领域通信协议的业界标准（De facto），并且现在是工业电子设备之间常用的连接方式。
通俗的讲，Modbus的本质就是通过寄存器、线圈与其它设备交换数据。

Modbus与Modbus TCP 、Modbus RTU、Modbus ASCII

Modbus是一簇协议，包含RTU、TCP、ASCII，Modbus并没有规定物理层。标准的Modicon控制器使用RS232C实现串行的Modbus协议。ASCII与RTU协议规定了信息、数据的结构、命令和应答的方式，采用Master/Slave方式，即Master端发出数据请求信息，Slave端接收到正确信息后就可以发送数据到Master端以响应请求；Master端也可以直接发送信息修改Slave端的数据，实现双向读写。
Modbus协议会对数据数据进行校验，ASCII采用LRC校验，RTU采用16位CRC校验，TCP由于可靠传输无需校验。
这三者的具体实现也有会所不同，TCP与RTU方式差别较小，具体参照详细。
总的来说Modbus TCP/RTU/ASCII这三者是Modbus协议的具体实现。最显而易见的就是，TCP通过以太网传输，RTU通过RS232C或RS422/RS485传输。

Modbus功能码

注：
常用的为1、2、3、4、15、16. 这6个功能即可实现对下位机数字量、模拟量的读写操作。

Node-RED中的Modbus

Flow

手头没有设备 暂时通过模拟演示
往常编写上位机程序可能需要手工根据数据格式构造数据封包，但目前有多别人造好的轮子装上就可以直接跑，何乐而不为？

安装Modbus节点

安装node-red-contrib-modbus

在Node-RED上模拟Modbus通讯

Modbus Server在本地127.0.0.1:10502以Modbus-TCP的方式模拟了一个Modbus Server。
其它设备可以直接通过Modbus-TCP直接连接该服务器。

Modbus Server

Server

端口尽量不要改动，如要改动要切换到管理员权限。

Modbus Client

Client

读操作

本例读取0~9号寄存器中的值
首先通过inject间断触发当前流，达到轮询效果。
在function中, 写入如下代码，fc为功能码，unitid为设备ID，address为地址，如读取多个寄存器为起始地址，quantity为数量，读取单个为1.

msg.payload = {
    'fc': 3,
    'unitid': 1,
    'address': 0,
    'quantity': 10
};
return msg;

其次，在function节点后添加Modbus Flex Getter节点，选择上一步添加的Client，该节点有两个输出，1号输出为读取的寄存器的值，可继续进行处理， 2号输出作为响应输入。

写操作

本例中随机生成10个int组成数组，写入0~10号寄存器
大致流程与读操作类似，function有一点不同

msg.payload = {
    'value': msg.payload,
    'fc': 16,
    'unitid': 1,
    'address': 0,
    'quantity': 10
};
return msg;

总体示例，导入的话，要添加Random节点

[{"id":"58a754a5.a3698c","type":"modbus-flex-getter","z":"788c6c48.cf2004","name":"","showStatusActivities":false,"showErrors":false,"logIOActivities":false,"server":"eaee2849.d0bd78","useIOFile":false,"ioFile":"","useIOForPayload":false,"x":465.5,"y":233,"wires":[["51569d6a.edb564"],["4c92ea01.f4acb4"]]},{"id":"f3754a33.823048","type":"modbus-flex-write","z":"788c6c48.cf2004","name":"","showStatusActivities":false,"showErrors":false,"server":"eaee2849.d0bd78","x":815.5,"y":297,"wires":[[],["d9df3e32.64265"]]},{"id":"2c9dfede.6b1562","type":"function","z":"788c6c48.cf2004","name":"fc3 1[0~9]","func":"msg.payload = {\n    'fc': 3,\n    'unitid': 1,\n    'address': 0,\n    'quantity': 10\n};\nreturn msg;","outputs":1,"noerr":0,"x":275.5,"y":233,"wires":[["58a754a5.a3698c"]]},{"id":"d6897fbf.b68c7","type":"inject","z":"788c6c48.cf2004","name":"","topic":"","payload":"","payloadType":"date","repeat":"0.5","crontab":"","once":false,"onceDelay":0.1,"x":110.5,"y":233,"wires":[["2c9dfede.6b1562"]]},{"id":"4c92ea01.f4acb4","type":"modbus-response","z":"788c6c48.cf2004","name":"","registerShowMax":20,"x":695.5,"y":239,"wires":[]},{"id":"1556b7fb.0614d8","type":"random","z":"788c6c48.cf2004","name":"","low":"0","high":"30","inte":"true","property":"payload","x":277.5,"y":299,"wires":[["ae9ce461.982f78"]]},{"id":"45cd92a5.68a16c","type":"function","z":"788c6c48.cf2004","name":"fc16 1[0~9]","func":"msg.payload = {\n    'value': msg.payload,\n    'fc': 16,\n    'unitid': 1,\n    'address': 0,\n    'quantity': 10\n};\nreturn msg;","outputs":1,"noerr":0,"x":607,"y":297,"wires":[["f3754a33.823048"]]},{"id":"ae9ce461.982f78","type":"join","z":"788c6c48.cf2004","name":"","mode":"custom","build":"array","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"10","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":425.5,"y":298,"wires":[["45cd92a5.68a16c"]]},{"id":"1c34ff31.4684f1","type":"inject","z":"788c6c48.cf2004","name":"","topic":"","payload":"","payloadType":"date","repeat":"0.1","crontab":"","once":false,"onceDelay":0.1,"x":110,"y":299,"wires":[["1556b7fb.0614d8"]]},{"id":"c9f27f2d.b30f3","type":"inject","z":"788c6c48.cf2004","name":"","topic":"","payload":"","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":97.5,"y":152,"wires":[["3317a601.2c860a"]]},{"id":"51569d6a.edb564","type":"debug","z":"788c6c48.cf2004","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":620.5,"y":150,"wires":[]},{"id":"3317a601.2c860a","type":"modbus-server","z":"788c6c48.cf2004","name":"","logEnabled":false,"hostname":"0.0.0.0","serverPort":10502,"responseDelay":100,"delayUnit":"ms","coilsBufferSize":10000,"holdingBufferSize":10000,"inputBufferSize":10000,"discreteBufferSize":10000,"showErrors":false,"x":336.5,"y":150,"wires":[["51569d6a.edb564"],["51569d6a.edb564"],["51569d6a.edb564"],["51569d6a.edb564"]]},{"id":"d9df3e32.64265","type":"modbus-response","z":"788c6c48.cf2004","name":"","registerShowMax":20,"x":1008.5,"y":344,"wires":[]},{"id":"eaee2849.d0bd78","type":"modbus-client","z":"788c6c48.cf2004","name":"","clienttype":"tcp","bufferCommands":true,"stateLogEnabled":false,"tcpHost":"localhost","tcpPort":"10502","tcpType":"DEFAULT","serialPort":"/dev/ttyUSB","serialType":"RTU-BUFFERD","serialBaudrate":"9600","serialDatabits":"8","serialStopbits":"1","serialParity":"none","serialConnectionDelay":"100","unit_id":1,"commandDelay":1,"clientTimeout":1000,"reconnectTimeout":2000}]

通过Modbus Slave在局域网模拟Modbus通信

在Modbus Slave中按F3配置连接，使用Modbus TCP/IP， 端口设置为502。

Connection Setup

建立多个 Slave以模拟不同的功能。

Modbus Slave

Modbus Client

按下述方式连接。function与上例相同。

Modbus连接

Node-RED 数据

Modbus Slave