EBUS Wolf cgb-2 - Device identification

I’ve made some little progress with a serial ebus adapter.
now my ebus device list is looking like this
openhab> ebus devices

MA | SA | Identifier     | Device         | Manufacture               | ID | Firmware   | Hardware   | Last Activity
---+----+----------------+----------------+----------------------+----+------------+------------+---------------------
FF | 04 |                | <interface>    | eBUS Library              |    | null       | null       | ---
   | 50 | 01 14 00 18 00 | ---            | G. Kromschröder AG        | 50 | 2.08       | null       | Wed Jan 15 23:22:20 CET 2020
   | 51 | 01 14 00 18 00 | ---            | G. Kromschröder AG        | 50 | 2.08       | null       | Wed Jan 15 23:22:21 CET 2020
10 | 15 |                | ---            | null                      |    | null       | null       | Wed Jan 15 23:22:23 CET 2020
30 | 35 |                | ---            | null                      |    | null       | null       | Wed Jan 15 23:22:20 CET 2020
70 | 75 |                | ---            | null                      |    | null       | null       | Wed Jan 15 23:22:21 CET 2020
71 | 76 | 01 15 00 00 80 | sm1            | G. Kromschröder AG        | 50 | 2.27       | null       | Wed Jan 15 23:22:25 CET 2020
03 | 08 | 01 06 33 42 02 | ---            | G. Kromschröder AG        | 50 | null       | 51.3       | Wed Jan 15 23:22:23 CET 2020
F1 | F6 |                | ---            | null                      |    | null       | null       | Wed Jan 15 23:22:24 CET 2020
07 | 0C |                | ---            | null                      |    | null       | null       | Wed Jan 15 23:10:33 CET 2020

However, I’m not able to get any proper values from the bus. The only value that can be read is
Temperature, solar cylinder 1 - 15.8°C which seem to be correct.
I’m trying to read e.g. Burner hours run from the Wolf CGB-2 (Slave 08) without success

Sometimes I see in the log
2020-01-15 23:37:21.338 [DEBUG] [.csdev.ebus.command.EBusCommandUtils] - Value temp_mixer with -100 is smaller then allowed 100

Any help / ideas?