How do you structure your "topic" string? the default in the application example is 'a/b' which does not enable any message to send/ publish.

I have a S7-1500 running the LMQTT function as per the application example and can connect to the ignition mqtt distributor, but not getting through to the engine. I found another thread here regarding subscribing that gave an example for the "topic"

if I start my topic string with the spbv1.0/ I can see the message come through on the gateway log but I'm getting the error:

Received DDATA for NULL edge node that didn't send a birth: spBv1.0/group_1/DDATA/plc_1/DeviceID

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Split from LMQTT Sparkplug.