Air Conditioning

Control Frame (ID 0x08) - Commands to Truma AC

Frame Format: [ID=08] [E0] [05] [72] [05] [FF] [FF] [32] [FF]

The control frame sends commands to the Truma air conditioning unit to set target temperature, operating mode, fan speed, and light brightness.

Bytes 0-1: Target Room Temperature and Mode

Combined 16-bit value (little-endian)

Bits 0-11: Target Room Temperature

• Format: 0.1°C resolution with -273°C offset
• Calculation: Temperature = (Raw Value × 0.1°C) - 273°C
• Range Examples:
  • 0x04BA - 0x0BE0: 16-31°C (Normal mode range)
  • 0x0B5E - 0x0BA4: 18-25°C (Auto mode range)

Bits 12-15: Temperature Control Mode

Encoding Example:

Bytes:  [0xE0] [0x05]
Binary: 0000 0101 1110 0000
        └─┬─┘└──────┬──────┘
        Mode   Temperature
         (0)   (1504 = 22.4°C)

Byte 2: Fan Mode

Fan speed control

Byte 3: Climate Mode

Operating mode control

Bytes 4-5: Reserved

Always 0xFF

These bytes are reserved and must be set to 0xFF.

Byte 6: Light Brightness

Interior light control (if supported by device variant)

• Range: 0-100 (0x00-0x64)
• Unit: Percentage brightness
• Resolution: 1% per bit
• Values:
  • 0x00: Light off (0%)
  • 0x32: 50% brightness
  • 0x64: 100% brightness (full)
  • 0xFF: Light not available/not used

Note: Light control is only available on devices with variant ID 0x01. Set to 0xFF for devices without light support (variant ID 0x00).

Byte 7: Reserved

Always 0xFF

This byte is reserved and must be set to 0xFF.

Info Frame (ID 0x17) - Status from Truma AC

Frame Format: [ID=17] [6C] [0B] [00] [00] [00] [C0] [00] [FF]

The info frame reports the current status of the Truma air conditioning unit, including actual room temperature, target settings, operating mode, and error status.

Bytes 0-1: Actual Room Temperature and Mode

Combined 16-bit value (little-endian)

Bits 0-11: Actual Room Temperature

• Format: 0.1°C resolution with -273°C offset
• Calculation: Temperature = (Raw Value × 0.1°C) - 273°C
• Example: 0x0B6C (2924) = (2924 × 0.1) - 273 = 19.4°C

Bits 12-15: Temperature Control Mode

Encoding Example:

Bytes:  [0x6C] [0x0B]
Binary: 0000 1011 0110 1100
        └─┬─┘└──────┬──────┘
        Mode   Temperature
         (0)   (2924 = 19.4°C)

Bytes 2-3: Target Room Temperature and Mode

Combined 16-bit value (little-endian)

Bits 0-11: Target Room Temperature

• Format: Same encoding as actual temperature
• Range Examples:
  • 0x04BA - 0x0BE0: 16-31°C (Normal mode range)
  • 0x0B5E - 0x0BA4: 18-25°C (Auto mode range)
• Special Value: 0x0000 (-273°C) indicates system off / no target set

Bits 12-15: Target Temperature Mode

Same encoding as bytes 0-1

Example:

Bytes: [0x00] [0x00]
Value: 0x0000 = System OFF (no target temperature)

Byte 4: Fan Mode

Current fan speed setting

Byte 5: Climate Status

Bit-encoded status byte

Bits 0-3: Current Climate Mode

Bit 4: Manual Control

• 0: Automatic operation
• 1: Manual control active

Bit 5: Error Status

• 0: No errors
• 1: Error condition present

Bits 6-7: Reserved

• Value: Always 11 (binary)
• Fixed bits for protocol identification

Decoding Example:

Byte 5: 0xC0 = 11000000 (binary)
               ││││└┴┴┴─ Bits 0-3: 0000 = Off
               │││└───── Bit 4: 0 = Automatic
               ││└────── Bit 5: 0 = No error
               └┴─────── Bits 6-7: 11 = Reserved (always set)

Byte 6: Light Brightness

Interior light control status

• Range: 0-100 (0x00-0x64)
• Unit: Percentage brightness
• Values:
  • 0x00: Light off (0%)
  • 0x32: 50% brightness
  • 0x64: 100% brightness (full)
• Resolution: 1% increments

Byte 7: Reserved

Always 0xFF

This byte is reserved for future protocol extensions and always contains the value 0xFF.