stefandreyer
commented
1 month ago Hi,
in sTopic you have to write the exact topic you what to receive, FB receiveString doesn't handle any of the wildcard characters of MQTT, please try this, else you have to implement your own FB like you did to handle multiple topics in one FB.
PayloadIsString ist set by your subscription FB, MQTT doesn'T makes a differecne in this,
BR Stefan
Hello Stefan, thank you for your work on the library! I have been able to publish to my Mosquitto-Broker on my PC, but I can not figure out how to properly subscribe to a channel or capture the messages correctly.
I think I am getting something mixxed up, because I am using an old Version (3.5.11 is the only Version I was able to get running on the old Codesys version supported by my PLC..).
This is how I can publish, it all works fine:
I have tried different ways of subscribing, this is what I am currently left with, from the example project, but I see no changes what so ever when I break at the receiver:
In the main task I simply call the sub and publish functions and the MQTT handler:
It would be very nice if you could give me a hint what I am missing or point me towards the right example version. (The date on my files is the 8.4.2019, if that helps.)
Edit: I changed the topic to '#', but still cant see anything. "Recived Publishs" in the MQTTSubscribe instance stays at 0 aswell. So I guess the subscriber does not get any of the messages (I can see them in Mosquitto though). I get a connection at the broker with the correct topic subscription. In the MQTTHandle instance I can see the "CounterOutputPublishCalled" increase with the messages I publish from my PC and "RevicedBytes" also increases whenever I publish a message to the broker (from my PC). When I added a breakpoint in the maintask to stop at every cycle, "CountReceivedPublishs" also increased, otherwise it did not. I also noticed that the first Entry of the InData Array in MQTT_Handle changes when a message is inbound.
Edit 2: I can see my reciveString object (showing the correct topic '#') in the SubscribeCalbacks array of MQTT_handle in my main Task. The MQTT_handles object shows some reaction to inbound messages, but it doesnt seem to be passed on to the next publishReceived Method.
Edit 3: I created my own subscription FB implementing the MessageRecived interface to see if the "MessageRecived" function gets called for a incoming message, which was very easy to do thanks to your great implementation. The call is executed as expected and I was also able to read the data, so there must be something I have done incorrectly when using the ReciveString. One thing I noticed is that for all messages "PayloadIsString" seems to be True and it doesnt matter if I put a string (with "quotes") or a number as the message in mosquitto.
I believe I can make my project work with my makeshift solution. However if anyone has an idea as to where I made a mistake and what I need to change, I would be thankfull for any hints.
Beste Grüße, Max