Help using UA Expert PubSub and MQTT

Questions regarding the use of the UaExpert.

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luismartin
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Help using UA Expert PubSub and MQTT

Post by luismartin »

Hello everybody,

This is my first message. My name is Luis Martin, and I am writing here because I need some help with the software UA Expert and its capacity to work with MQTT.

More especifically, I have a network with three computers. One is running a OPC UA server that is sending information using MQTT (in other words, a MQTT publisher). In other computer I have a Mosquitto broker, which is receiving the data published by the OPC UA Server. The third computer is running UA Expert and I want to subscribe to the MQTT topic to receive everything that the OPC UA Server is publishing. However, I don't know how to do it.

I have followed the instructions that I found about how to use the OPC UA PubSub capacities implemented by UA Expert, but I am afraid that I am too clumsy and I am not capable of running it. Therefore, I need help about how to set up UA Expert to connect with the Mosquitto broker. Any help would very appreciated.

Best,
Luis

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Support Team
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Re: Help using UA Expert PubSub and MQTT

Post by Support Team »

Hi,

to receive the data with UaExpert you just need to "delete" the MQTT broker, and you just need to "delete" the MQTT Publisher from your scenario. When using the (mandatory) OPC UA Binary encoding with TCP/IP and UA secure conversation, you will get the data secured and directly into UaExpert. UaExpert is designed to use OPC UA Client/Server with binary encoding over TCP/IP. In order to traverse Firewall, the UaExpert is capable of doing the reverse connect.

Converting and sending the data from an OPC UA enabled device with UA Publisher over MQTT to a MQTT Broker and consuming the data on the other side with MQTT subscriber, only makes sense if you either have already a MQTT subscriber, or you want to write yourself some MQTT subscriber. Maybe because you think it is "simpler" and "easier" compared to just using an OPC UA Client (e.g. if you have some Web or Cloud application, that is not able to do OPC UA Client/Server directly). However, UaExpert is not a Cloud-Application (and for sure not a Web-Application), hence UaExpert is able to do the UA Client/Server directly.
Best regards
Unified Automation Support Team

luismartin
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Re: Help using UA Expert PubSub and MQTT

Post by luismartin »

Hi Support Team,

Thank you very much for your answer, but I think I haven't made myself clear.

I have a MQTT broker running on a computer with the IP 192.168.31.50. In addition, I have another computer (192.168.31.51) running an OPC UA server and sending information using OPC UA over MQTT (the publisher). What I need is to configure a third computer (192.168.31.52) running UaExpert, so that UaExpert may subscribe to the MQTT broker to receive the data (the subscriber). However I don't know how to do it, because the UaExpeter graphical interface is a bit confusing to me.

I have added a new pubsub document. I have set up the MQTT broker, as well as the connection settings. However now I have to set up the Writer and the Reader. To be honest, I don't understand why I have to set up the writer, because I want to read, not to write. Anyway, it seems that the reader configuration depends on the writer configuration, so I tried to do my best, setting up the queue name. However I am lost. It is not working. I don't read anything.

What I need to know is the right sequence of steps to set up the MQTT reader.

Best,
Luis

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Support Team
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Re: Help using UA Expert PubSub and MQTT

Post by Support Team »

Hi,
What I need is to configure a third computer (192.168.31.52) running UaExpert, so that UaExpert may subscribe to the MQTT broker to receive the data (the subscriber).
the UaExpert is not doing any MQTT nor any PubSub, neither reading nor writing. The UaExpert is doing "pure" OPC UA Client, and by this can configure OPC UA Servers and tell them what to publish and what to subscribe. But this is "configuration of others" only, the UaExpert itself can not do any MQTT, nor any PubSub, just configuration via UA-TCP
Best regards
Unified Automation Support Team

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