[main error] scan config 05: ERR: read timeout

[HiQual]

Hello
ebusd is working very well for me - thank you very much.
I am using a danielkucera/esp8266-arduino-ebus adapter v2 with only a Vaillant boiler.
There are no other devices or controllers on the ebus.
My configuration is /usr/bin/ebusd --scanconfig -d esp-ebus.local:3333 --latency=90
My query is the subject error message in the ebusd log - [main error] scan config 05: ERR: read timeout.
I would like to know what is "05" because it does not appear in ebusctl i ...

nor ebusctl find

Many thanks.