Raspberry Pi, Siemens PLC, and Alibaba Cloud Integration

1. Configuration of Node-Red nodes in Raspberry Pi;

Since 2015, Node-Red and Node.js have been included by default. To prevent using an older version of Node-Red, you can connect to the Raspberry Pi using Putty and run the following command to update:

update-nodejs-and-nodered

The next step is to install npm, which makes it easier to add nodes to Node-Red on the Raspberry Pi. The steps are as follows:

Before installing npm, run the following command to update the Raspberry Pi system to the latest version, then restart the Raspberry Pi:

sudo apt-get update && apt-get upgrade

After restarting, run the following command to install npm:

sudo apt-get install npm

At this point, the preliminary preparation work on the Raspberry Pi is basically complete. Connect to the Raspberry Pi using Putty and run Node-Red;

Then enter http://{Raspberry Pi’s address}:1880/ in the browser to access the Node-Red editing interface, as shown in the following image:

Since S7 is a proprietary protocol of Siemens PLC, Node-Red does not come with this node by default. You need to install it yourself (if npm has not been installed previously, installing new nodes will be quite troublesome). As shown in the image, open the node management in Node-Red settings, search for S7, and install the second node;

After installation, you will see the S7 node appear on the left;

At this point, the setup of Node-Red is basically complete. Next, we will do some simple programming. The pros and cons of Node-Red programming will not be elaborated here. If you are not familiar with Node-Red programming, you can refer to the link: https://zhuanlan.zhihu.com/p/27546140;

The nodes that will be used this time include S7 in; S7 out; MQTT in; MQTT out;

First, we will set up the S7 in node:

Fill in the PLC’s IP address in the IP Address field, the port defaults to 102, and select Rack/Slot for the mode. The default rack number for the PLC is 0, and the slot number is 1;

Next, fill in the variables to be accessed, corresponding to the settings in TIA Portal;

Next, we set up the S7 out node;

The Out node setup is similar to the In node. Here we choose to modify the variable to be 1.

At this point, the S7 node setup is complete. Next, we will set up the MQTT in and MQTT out nodes as shown in the following images;

First, we set up the Out node:

In the above image, fill in the public IP of Alibaba Cloud for the server IP, the port number is 61613 (the TCP port number), the client ID can be left blank, and the username and password are the credentials for the MQTT server deployed on Alibaba Cloud (default username is admin, password is password);

In the topic field, fill in the topic you want to subscribe to from the MQTT server;

All the nodes above have been configured. Connect the nodes and click the deploy button in the upper right corner to deploy Node-Red to the Raspberry Pi;

The first part ends here.