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PowerConsumptionHmu and Errorhistory decode errors in 08.hmu.HW5103.csv (Vaillant aroTHERM) #638

Description

@MarkBovee

Device

Hardware: Vaillant aroTHERM VWL 55/5 AS
Address 08 (HMU): MF=Vaillant, ID=HMU00, SW=0522, HW=5103
ebusd version: 26.1.26.1
Config source: https://ebus.github.io/de/
Loaded file: vaillant/08.hmu.HW5103.csv

Bug 1: PowerConsumptionHmu (b516,14) — "invalid position"

CSV line: r,,,PowerConsumptionHmu,,,,b516,14,ign,,IGN:1,,,,value,,EXP,1000,kW,

Raw hex query: 3108b5160114 (QQ=31, ZZ=08, PB=B5, SB=16, NN=01, DD=14)
Raw response: 00 (single byte 0x00)

Problem: The definition has IGN:1 (skip 1 byte) followed by EXP (2+ byte exponential). The bus response is only 1 byte total. The IGN:1 consumes that byte, then the EXP decode at position 1 fails with "invalid position" because there is no second byte.

The 00 response likely is the power value (0 W when compressor is idle), making the IGN:1 incorrect — it should not be there. If we strip the IGN, the value should decode as a single-byte unsigned integer with divisor 1000 → 0 kW.

Bug 2: Errorhistory (b503,0101) — "invalid position"

CSV line: r,,,Errorhistory,Fehlerhistorie,,,b503,0101,index,m,UCH,,,,status,,UCH,,,Status,time,,VTM,,,Uhrzeit,date,,HDA:3,,,Datum,error,,UIN,,,Fehlernummer

Raw hex query: 3108b503020101 (QQ=31, ZZ=08, PB=B5, SB=03, NN=02, DD=0101)
Raw response: 00 (single byte 0x00)

Problem: The definition expects 5+ fields (index UCH, status UCH, time VTM, date HDA:3, error UIN). The response is only 1 byte. The first field index(UCH) reads byte 0x00 successfully, but status(UCH) at position 1 fails.

00 likely means "no error at this index" or "error list is empty" (hwc compressor not running, no errors to report).

Notes

  • Both definitions are in the HW5103-specific override file 08.hmu.HW5103.csv. The base 08.hmu.csv does not define these registers.
  • These are not critical (compressor power is also available via RunDataElectricPowerConsumption in B509 messages, though that register is also missing from the HW5103 override file), but the decode errors show up in find output and the registers remain unavailable.
  • The 14 field ID for PowerConsumptionHmu successfully reaches the device (valid response), but the data format does not match the default definition.
  • Errorhistory likely requires looping over indices until "no data stored"; the single-byte 00 response at index 01/01 may need a different interpretation or the message might need a different hex structure for HW5103.

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