New TIN Protocol

Overview

The New TIN protocol is used by modern Truma heating devices (TIN 4.0, mid-2018 onwards). Unlike the Legacy TIN protocol with separate command frames, New TIN features a unified command structure where all heating parameters are sent in a single frame.

This protocol is used by:

Modern Truma Combi heaters (2018+)
InetX control panels
iNet X Connect remote modules
Modern Aventa air conditioning units

Signal Frame Types

Signal ID	Frame Type	Direction	Purpose
0x20	Heater Command	Master → Slave	Unified heater control
0x21	Heater Info 1	Slave → Master	Temperature telemetry
0x22	Heater Info 2	Slave → Master	Power and system status
0x17	Aircon Command	Master → Slave	Air conditioning control

Heater Command (0x20)

The unified command frame controlling all heater functions.

Frame Structure

Byte	0	1	2	3	4	5	6	7
Content	Room Temp Code	Control Flags	Water Temp	Fuel Control	Electro Power	Vent + Energy	0xE0	0x0F
Function	Target temp	Boiler/Heat	Water level	Gas enable	Electric power	Fan + bitmap	Fixed	Fixed

Byte 0: Room Temperature Code

Temperature is encoded using the following formula:

code = (220 + (temp - 5) * 10) % 256
temp = ((code - 220) % 256) / 10 + 5

Special case: 0xAA = Off

Temperature Range: 5-30°C (in 1°C steps)

Byte 1: Control Flags

Bit	Function	Values
7	Boiler enable	0 = On, 1 = Off (inverted!)
0	Heating enable	0 = Off, 1 = On
1-6	Base pattern	Always `0x2A` (binary: `0010 1010`)

Common Values:

0x2A (0010 1010): Boiler ON, Heating OFF
0x2B (0010 1011): Boiler ON, Heating ON
0xAA (1010 1010): Boiler OFF, Heating OFF
0xAB (1010 1011): Boiler OFF, Heating ON

Byte 2: Water Temperature Level

Code	Level	Temperature	Description
`0xAA`	Off	-	Water heating disabled
`0xC3`	Eco	~40°C	Energy-saving hot water
`0xD0`	Hot	~60°C	Maximum hot water

Byte 3: Fuel Control

Value	Function
`0x00`	Fuel disabled
`0xFA`	Fuel enabled (gas/diesel heating active)

Byte 4: Electric Power Level

Code	Power Level	Watts
`0x00`	Off	0W
`0x09`	Low	900W
`0x12`	High	1800W

Byte 5: Ventilation + Energy Bitmap

Upper Nibble (bits 4-7): Ventilation Level

Nibble	Level	Description
`0x0`	Off	Ventilation disabled
`0x1`	Level 1	Manual minimum
`0x2`	Level 2	Manual low
`0x3-0x9`	Levels 3-9	Manual intermediate levels
`0xA`	Level 10	Manual maximum
`0xB`	Comfort	Automatic comfort mode
`0xD`	Boost	Maximum boost mode

Lower Nibble (bits 0-3): Energy Bitmap

Bit	Function
0	Fuel enabled (mirrors byte 3)
1	Electro enabled (derived from byte 4)
2-3	Reserved

Common Patterns:

0xB0 = Comfort mode, no energy
0xB1 = Comfort mode, fuel only
0xB2 = Comfort mode, electric only
0xB3 = Comfort mode, fuel + electric (mix)

Bytes 6-7: Fixed Values

Byte 6: Always 0xE0
Byte 7: Always 0x0F

Example Frames

Everything off:

[0xAA] [0xAA] [0xAA] [0x00] [0x00] [0x00] [0xE0] [0x0F]

Heat room to 22°C, water Eco, fuel only, comfort fan:

[0x86] [0x2B] [0xC3] [0xFA] [0x00] [0xB1] [0xE0] [0x0F]
 │      │      │      │      │      │
 │      │      │      │      │      └─ Comfort mode (0xB), fuel bit set (0x1)
 │      │      │      │      └─ Electric off
 │      │      │      └─ Fuel enabled
 │      │      └─ Water Eco (40°C)
 │      └─ Boiler on (bit 7=0), heating on (bit 0=1), pattern 0x2A
 └─ Room 22°C

Heat room to 28°C, water Hot, mix mode (fuel + 900W), boost fan:

[0xC2] [0x2B] [0xD0] [0xFA] [0x09] [0xD3] [0xE0] [0x0F]
 │      │      │      │      │      │
 │      │      │      │      │      └─ Boost mode (0xD), fuel + electro bits (0x3)
 │      │      │      │      └─ Electric 900W
 │      │      │      └─ Fuel enabled
 │      │      └─ Water Hot (60°C)
 │      └─ Boiler on, heating on
 └─ Room 28°C

Water heating only (no room heating), Hot water, fuel:

[0xAA] [0x2A] [0xD0] [0xFA] [0x00] [0x01] [0xE0] [0x0F]
 │      │      │      │      │      │
 │      │      │      │      │      └─ Fan off, fuel bit set
 │      │      │      │      └─ Electric off
 │      │      │      └─ Fuel enabled
 │      │      └─ Water Hot
 │      └─ Boiler on, heating off
 └─ Room heating off

Manual ventilation level 5, no heating:

[0xAA] [0xAA] [0xAA] [0x00] [0x00] [0x50] [0xE0] [0x0F]
                                     │
                                     └─ Level 5 (0x5), no energy

Heater Info 1 (0x21)

Reports current room and water temperatures.

Frame Structure

Byte	0	1	2	3-7
Content	Room Temp (low 8 bits)	Room (high 4 bits) + Water (low 4 bits)	Water Temp (high 8 bits)	Reserved
Encoding	12-bit packed	Shared byte	12-bit packed	Padding

Temperature Encoding

Temperatures are encoded as 12-bit values representing Kelvin × 10, packed into 3 bytes.

Room Temperature:

room_encoded = (byte1 & 0x0F) << 8 | byte0
room_celsius = (room_encoded / 10.0) - 273.0

Water Temperature:

water_encoded = byte2 << 4 | (byte1 & 0xF0) >> 4
water_celsius = (water_encoded / 10.0) - 273.0

Example Frame

Room at 22.5°C, water at 45.3°C:

Step 1: Encode temperatures

room_kelvin_x10 = (22.5 + 273.0) × 10 = 2955
water_kelvin_x10 = (45.3 + 273.0) × 10 = 3183

Step 2: Pack into bytes

room_encoded = 2955 = 0x0B8B (12-bit)
  byte0 = 0x8B (low 8 bits)
  byte1_low = 0x0B (high 4 bits)

water_encoded = 3183 = 0xC6F (12-bit)
  byte2 = 0xC6 (high 8 bits)
  byte1_high = 0x0F (low 4 bits)

byte1 = (0x0F << 4) | 0x0B = 0xFB

Frame:

[0x8B] [0xFB] [0xC6] [0x00] [0x00] [0x00] [0x00] [0x00]
 │      │      │
 │      │      └─ Water high 8 bits (0xC6)
 │      └─ Room high 4 bits (0x0B) + Water low 4 bits (0x0F)
 └─ Room low 8 bits (0x8B)

Decoding Example

Given frame: [0x9F] [0xBB] [0xB7] [0x28] [0x12] [0x02] [0xF0] [0x0F]

Room Temperature:

room_encoded = ((0xBB & 0x0F) << 8) | 0x9F
             = (0x0B << 8) | 0x9F
             = 0x0B9F = 2975
room_celsius = 2975 / 10.0 - 273.0 = 24.5°C

Water Temperature:

water_encoded = (0xB7 << 4) | ((0xBB & 0xF0) >> 4)
              = (0xB7 << 4) | 0x0B
              = 0xB7B = 2939
water_celsius = 2939 / 10.0 - 273.0 = 20.9°C

Heater Info 2 (0x22)

Reports power supply status and boiler state.

Frame Structure

Byte	0	1	2	3-7
Content	Voltage	System Flags	Boiler State	Reserved

Byte 0: Voltage

Encoding: Voltage × 100mV

Example:

0x84 = 132 → 13.2V
0x85 = 133 → 13.3V
0x77 = 119 → 11.9V

Byte 1: System Flags

Bit	Function	Values
5	230V AC supply	0 = Not present, 1 = Present
6	AC auto mode	Status indicator
7	Pump running	0 = Off, 1 = Running
0-4	Reserved	Various status bits

Common Values:

0x20: 230V present, pump off
0x60: 230V present, additional flag set
0x70: 230V present, pump running
0x30: 230V present, different status

Byte 2: Boiler State

Code	State	Description
`0x10`	Eco reached	Water at Eco temperature (~40°C)
`0x11`	Eco heating	Actively heating to Eco
`0x30`	Hot reached	Water at Hot temperature (~60°C)
`0x31`	Hot heating	Actively heating to Hot
`0x04`	Error/Other	Alternative status code
`0x05`	Error/Other	Alternative status code

Example Frames

13.2V, 230V present, Eco temperature reached:

[0x84] [0x60] [0x10] [0x05] [0xFF] [0xFF] [0xFF] [0xFF]

11.9V, 230V present, pump running, Hot water active:

[0x77] [0x70] [0x31] [0x05] [0xFF] [0xFF] [0xFF] [0xFF]

13.3V, 230V present, heating inactive:

[0x85] [0x20] [0x10] [0x05] [0xFF] [0xFF] [0xFF] [0xFF]

Aircon Command (0x17)

Controls air conditioning units on the TIN bus.

Frame Structure

Byte	0-7
Content	AC control data

Note: The exact format for AC control requires further analysis. The signal is used for Truma Aventa and Saphir air conditioning units.

Complete Control Sequence Example

Scenario: Cold morning startup

Step 1: Master sends Heater Command (0x20)

Target: Room 22°C, Water Eco, Fuel only, Comfort fan
[0x86] [0x2B] [0xC3] [0xFA] [0x00] [0xB1] [0xE0] [0x0F]

Step 2: Heater responds with Info 1 (0x21)

Current: Room 15.5°C, Water 12.0°C (cold start)
[0x5A] [0xAB] [0xBC] [0x3C] [0x12] [0x01] [0xF0] [0x0F]

Step 3: Heater responds with Info 2 (0x22)

Voltage: 13.2V, 230V present, Eco heating active
[0x84] [0x60] [0x11] [0x05] [0xFF] [0xFF] [0xFF] [0xFF]

Step 4: After 30 minutes, Info 1 update

Current: Room 21.5°C, Water 39.5°C (approaching target)
[0x7A] [0xBB] [0xC3] [0x3C] [0x12] [0x01] [0xF0] [0x0F]

Step 5: Target reached, Info 2 update

Voltage: 13.2V, 230V present, Eco temperature reached
[0x84] [0x60] [0x10] [0x05] [0xFF] [0xFF] [0xFF] [0xFF]

Implementation Notes

Temperature Encoding

Room Temperature (Byte 0): Uses the formula (220 + (temp - 5) * 10) % 256 where temp is in Celsius (5-30°C). Special case: 0xAA = Off.

Telemetry Temperatures (Frame 0x21): Encoded as 12-bit values representing Kelvin × 10, packed into bytes.

Advantages over Legacy TIN

Single Frame: All parameters in one frame (0x20) vs. 5 separate frames
Efficient: Reduced bus traffic and simpler state management
Atomic Updates: All parameters updated simultaneously
Modern Features: Better support for mix mode, detailed status reporting

Migration from Legacy TIN

When supporting both protocols:

Detection: Use product identification to determine device generation
- Function ID 0x0301 or 0x0310 → Legacy TIN
- Function ID 0x0340 or 0x0320 → New TIN

Abstraction Layer: Create unified API that maps to appropriate protocol:

trait HeaterControl {
    fn set_room_temp(&mut self, celsius: u8);
    fn set_water_temp(&mut self, level: WaterLevel);
    fn set_fuel_enabled(&mut self, enabled: bool);
    fn set_electro_power(&mut self, watts: u16);
    fn set_fan_level(&mut self, level: FanLevel);
}

Frame Generation: Convert high-level commands to protocol-specific frames

References

TIN Protocol Overview - General TIN protocol information
Legacy TIN Protocol - Legacy protocol specification
Implementation: womonet-drivers/src/tin/protocol/tinnew/
Test Data: truma-driver/logs_new.md