MQTT basics and understanding

PLCnext Store
1

Hey PLCnext Support Team:

I have a few questions after watching the coding diary MQTT videos on you tube as I’d like to give MQTT a spin. I’m working with a windows 10 computer and a PLCnext demo (AXC F 2152, 2020.0 firmware edition, order# 2404267). Also, I have learned to implement the example eclipse C++ program on my controller successfully so far. What I’d like to do is really try out each MQTT for demo purposes and currently I’m at the stage where I want to download Mosquitto MQTT from PLC next sore and it is asking me some information. For starters, when I’m downloading this am I actually downloading it to the controller and not the computer? Would this make my controller a “broker”? Upon opening up the library on the store, I’m being asked to “Select device” and am given a text entry field. I click on this and am then asked for a device UUID and Name of the device. I’ve attached this dialog box to this message. Where do I find these things for my controller (if my controller is what “device” is referring to)? Thanks, Brendan

2

Hi Brendan,

when I’m downloading this am I actually downloading it to the controller and not the computer?

Yes. All apps from the PLCnext Store are downloaded to the controller, apart from “Library” apps which are designed to be used with PLCnext Engineer.

Would this make my controller a “broker”?

In the case of the Mosquitto app, yes. The app also includes the mosquitto client tools (e.g. mosquitto_pub and mosquitto_sub), so you can also use these on the controller.

Where do I find these things for my controller (if my controller is what “device” is referring to)?

Yes, the controller is the device in this case. The UUID should be printed on the side of the controller, or you can see it in the Web-Based management page. The device name can be whatever you want. There is more information in the PLCnext Store Info Center. ~ Martin.