Hello Klaus
If I read your message correctly, then you have connected a wallbox which has a RS485 Interface using a converter, which offers MQTT as an interface.
You did not explain what kind of wallbox you are using in your setup. Giving any hints without that information is difficult.
You work with the following chain:
wallbox <-RS485-> converter <-TCP/MQTT -> node-red (MQTT-in/out node)
I suggest to reduce some complexity, and connect directly to the converter using the webpage offered by the converter, or using TELNET.
That way you can test the commands and answers directly using a web browser or a terminal. Only after this works to your satisfaction, I suggest to then add node-red.
But to help more, we need more information about about the wallbox.
Kind regards,
Urs.
