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fix: consumer Lambda #4269

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LKuemmel merged 2 commits into from
Nov 6, 2026
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fix: consumer Lambda #4269

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8f54b48
Lambda consumer: encode EVU power as signed int16 to fix crash on neg…
seaspotter Nov 5, 2026
5b1e8a4
Lambda consumer: encode register 102 as signed int16, align set_power…
seaspotter Nov 5, 2026
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9 changes: 7 additions & 2 deletions packages/modules/consumers/lambda_/lambda_/consumer.py
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,8 @@ def send_values(values: CurrentValues) -> None:
# Wärmepumpe selbst auf Datenquelle "Modbus Client" umgestellt werden (Kap. 4.3),
# das kann openWB nicht per Modbus setzen. Wird vom Core automatisch aufgerufen,
# solange dieser Verbraucher als ConsumerUsage.SELF_CONTROLLED konfiguriert ist.
client.write_register(102, values.evu_power, wordorder=Endian.Little, unit=config.configuration.modbus_id)
client.write_register(102, values.evu_power, data_type=ModbusDataType.INT_16,

@sourcery-ai sourcery-ai Bot Nov 5, 2026

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🟠 High · Signed power writes fail

When the EVU value is negative, a positive power limit is negated, or a float power value reaches the write, ModbusClient.write_register passes 16-bit values directly to pymodbus instead of encoding them as signed register words, so negative EVU values and negated limits are rejected; float values also reach pymodbus without integer conversion. The register write fails, and the Lambda does not receive the EVU or power-limit update.

Encode signed 16-bit values into valid register words, and convert float power inputs to integers, before calling pymodbus.

Also at packages/modules/consumers/lambda_/lambda_/consumer.py:47-48.

Prompt for AI agents 
In `packages/modules/consumers/lambda_/lambda_/consumer.py` at line 32:

**Signed power writes fail**

When the EVU value is negative, a positive power limit is negated, or a float power value reaches the write, `ModbusClient.write_register` passes 16-bit values directly to pymodbus instead of encoding them as signed register words, so negative EVU values and negated limits are rejected; float values also reach pymodbus without integer conversion. The register write fails, and the Lambda does not receive the EVU or power-limit update.

Encode signed 16-bit values into valid register words, and convert float power inputs to integers, before calling pymodbus.

Also at `packages/modules/consumers/lambda_/lambda_/consumer.py:47-48`.

wordorder=Endian.Little, unit=config.configuration.modbus_id)

def update() -> ConsumerState:
power = client.read_holding_registers(
Expand All @@ -39,8 +40,12 @@ def update() -> ConsumerState:
def set_power_limit(power_limit: float, data: SetLimitData) -> None:
# Schreibt den von openWB berechneten Überschuss in Register 102 (E-Manager Bezug/Einspeisung).
# Keine echte Leistungsvorgabe - die Wärmepumpe regelt weiterhin selbst anhand dieses Wertes.
# Negiert wie in send_values(), da der E-Manager auf "Neg. E-Überschuss" eingestellt sein muss
# (negativ = Überschuss) - ohne das Minus würde eine zugeteilte Leistung als Fehlbetrag
# missverstanden.
client.write_register(102,
max(power_limit, 0),
-max(power_limit, 0),
data_type=ModbusDataType.INT_16,
wordorder=Endian.Little,
unit=config.configuration.modbus_id)

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