TIN Protocol

Overview

TIN (Truma Intelligent Network) is Truma’s implementation of the LIN (Local Interconnect Network) protocol for controlling heating, cooling, and ventilation systems in recreational vehicles. The protocol runs at 9600 baud (compared to the standard automotive LIN speed of 19,200 baud) and uses an RJ12 connector where PIN 3 is LIN/TIN and PIN 5 is GND. Moover units use a Rast 2.5 connector instead.

Technical Foundation

LIN Transport Layer

TIN is built on the LIN 2.x protocol standard:

• Baud Rate: 9600 bps (Truma-specific, lower than standard LIN)
• Bus Architecture: Single-wire plus ground
• Topology: Master-slave with multiple slave nodes
• Frame Format: Header (master) + Response (slave)
• Data Length: 8 bytes per frame

Frame Structure

Every LIN/TIN frame follows this structure:

[SYNC_BREAK] [SYNC_FIELD] [PID] [DATA_0..7] [CHECKSUM]

Protected Identifier (PID):

• Size: 1 byte
• Format: PPFFFFFF (2 parity bits + 6 frame ID bits)
• Frame Types:
  • 0x00-0x3B: Signal frames (unconditional)
  • 0x3C: Master request frames (diagnostic)
  • 0x3D: Slave response frames (diagnostic)
  • 0x3E: User defined frames
  • 0x3F: Reserved protocol frames

Checksum:

• Classic Checksum: Used for diagnostic frames (0x3C-0x3F)
• Enhanced Checksum: Used for signal frames (includes PID in calculation)

Connector Specifications

RJ12 Connector (Standard):

• PIN 3: LIN/TIN signal
• PIN 5: GND (Ground)

Rast 2.5 Connector (Moover units):

• Used for diagnostic purposes on Moover components

Protocol Versions

TIN has evolved through several versions, each adding new capabilities and supporting different device generations.

TIN 1.0 (Legacy)

• Purpose: Diagnostic use only
• Devices: Heaters with analog control panels, early CP-Plus units (non-I-Net Ready)
• Limitations: No remote control capability
• Status: Obsolete for modern installations

TIN 3.2 (I-Net Ready)

• Introduction: First I-Net Ready protocol version ()
• Devices: I-Net Ready heaters with firmware ≥ 5.0.0
• Features: Remote control via Inet Box, CP Plus control
• Compatibility: Cannot work with newer InetX panels

TIN 4.0 (Current)

• Introduction: Mid-2018
• Devices: Modern heaters, InetX panels, iNet X Connect
• Features: Full remote control, Bluetooth connectivity (InetX), mobile network (Connect)
• Backward Compatibility: Supports analog control panels
• Status: Current standard for new installations

Device Identification

Manufacturer ID

All Truma devices use the manufacturer ID: 0x4617 (little-endian: [0x17, 0x46])

Product Types and Function IDs

Heaters

Air Conditioners

Discovery Process

Device discovery uses the Read By Identifier service (SID 0xB2):

1. Product Identification Request:

[PID=0x3C] [NAD] [PCI=0x06] [SID=0xB2] [ID=0x00] [0x17] [0x46] [FUNC_ID_LO] [FUNC_ID_HI]

2. Product Identification Response:

[PID=0x3D] [NAD] [PCI=0x06] [RSID=0xF2] [0x17] [0x46] [FUNC_ID_LO] [FUNC_ID_HI] [VARIANT]

3. Serial Number Request:

[PID=0x3C] [NAD] [PCI=0x06] [SID=0xB2] [ID=0x01] [0x17] [0x46] [FUNC_ID_LO] [FUNC_ID_HI]

4. Serial Number Response:

[PID=0x3D] [NAD] [PCI=0x06] [RSID=0xF2] [SERIAL_BYTE0] [SERIAL_BYTE1] [SERIAL_BYTE2] [SERIAL_BYTE3]

Identifier Types

• 0x00: Product Identification (manufacturer ID + function ID + variant)
• 0x01: Serial Number (32-bit, little-endian)
• 0x20: Firmware Version (major.minor.revision.build)
• 0x23: Current Error Status

Service Identifiers

Request Services (SID)

Response Services (RSID)

Error Handling

Error Format

Device errors are encoded in 3 bytes:

Byte 0: Error Format (0x01 or 0x02)
Byte 1: Error Class
Byte 2: Error Code

Error Classification

Format 1:

• class = 0x00: OK (no error)
• class < 0x10: Warning
• class ≥ 0x10: Error

Format 2:

• class = 0x00: OK (no error)
• class < 0x05: Warning
• class ≥ 0x05: Error

Display Format

Errors are typically displayed as: {SEVERITY}{CLASS}{CODE} {DEVICE}

Examples:

• E621 H - Error, class 6, code 21, Heater
• W423 H - Warning, class 4, code 23, Heater
• O000 H - OK (no error)

Signal Protocols

TIN supports three signal protocol variants for different device generations:

• Legacy TIN Protocol →

  Legacy heaters (TIN 1.0/3.2) with separate command channels for each function. Signal IDs: 0x03-0x07, 0x16.

• New TIN Protocol →

  Modern heaters (TIN 4.0, mid-2018+) with unified command structure. Signal IDs: 0x20-0x22, 0x17.

Communication Patterns

Master-Slave Model

• Master: Control panel (CP Plus, InetX) sends commands and schedules signal transmission
• Slaves: Heaters, AC units respond to requests and transmit scheduled signals
• Timing: Frame intervals typically 10-100ms, with periodic status updates

Periodic Signal Transmission

1. Master sends sync break + sync field
2. Master transmits PID for expected signal
3. Slave transmits signal data + checksum
4. Master validates checksum
5. Process repeats for next scheduled signal

Command-Response Cycle

1. Master sends diagnostic/identification request (PID 0x3C)
2. Slave processes request
3. Slave sends response frame (PID 0x3D)
4. Master validates response
5. Communication continues

Known Components

Control Panels

Truma CP Plus:

• LIN Master in the TIN ecosystem
• Available in two variants:
  • Standard: Single TIN RJ12 connection
  • CI Variant: Additional RJ12 for CI-bus (rare, dealer-only)
• Older versions don’t support newer protocols (hardware identical, firmware locked)

Truma InetX:

• Modern control panel with resistive touchscreen
• Integrated Bluetooth for local app control
• TIN 4.0 only (mid-2018 onwards)
• Two versions:
  • Standard: TIN + Bluetooth
  • Pro: TIN + Bluetooth + CAN + CI-bus (CI-bus software-activated)
• Different cutout than CP Plus (not compatible)

Heaters

Truma Combi (2/4/6, E and D variants):

• Standard Truma heaters
• 2 RJ12 TIN connections on control unit
• Gray housing: Requires control unit replacement for I-Net Ready (no field update)
• Mid-2018+ units: TIN 4.0 with new control unit
• Analog control panels still compatible
• Operates as LIN slave

Air Conditioning

Truma Aventa:

• RJ12 connection for TIN bus
• Often not connected during installation
• Can be controlled via CP Plus, InetX, or Alde panels when connected

Alde Heaters (newer models):

• Red RJ12: TIN connection
• Yellow RJ12: CI-bus connection
• CI-bus always active (unlike Truma)
• Compatible with Truma ecosystem

Remote Solutions

Truma Inet Box (Legacy):

• GSM modem + Bluetooth interface
• Bluetooth for initial setup
• SMS for remote control
• 2 TIN 1 connections (slave mode to CP Plus)
• 1 TIN 2 connection (master mode to Aventa Comfort)
• Supports both TIN 3.2 and TIN 4.0
• Status: Obsolete (GSM shutdown ~2025 in Germany)

Truma iNet X Connect (Current):

• Introduced 2024
• Mobile network connectivity (40 European countries)
• Works with iNet X (Pro) panels
• CAN bus integration
• 2-year service package included
• Additional packages: 30-day or 365-day
• Price: €399 (specialist dealers)
• Status: Current official remote solution

Diagnostic Tools

Truma Service Interface:

• Based on BabyLIN Interface (Lipowsky)
• Windows software for diagnosis
• Live Explorer for real-time parameter monitoring
• Supports all Truma TIN components
• Status: Professional/expensive diagnostic tool

Truma Moover:

• Rast 2.5 connector for TIN
• Diagnostic purposes only

Communication Timing

Based on observed behavior:

Startup:

• Break duration: ~1.3ms
• Initial pause: ~1600ms

Periodic Communication:

• Frame interval: ~40-60ms
• Keepalive block: ~40 frames
• Keepalive frequency: Every 10 seconds

Frame Sequence (Example):

0x20 (HeaterCommand)
0x61 (no response)
0xE2 (no response)
0x3C (diagnostic request)
0x7D (no response)
[repeat...]
0x61 (0x21 response - HeaterInfo1)
0xE2 (0x22 response - HeaterInfo2)
0x3C (diagnostic)

Implementation Notes

Temperature Encoding

TIN uses two different temperature encoding schemes:

Legacy TIN: Kelvin × 10, 16-bit little-endian

• Off: 0x0000
• 5°C: 0x0ADC (2780)
• 22°C: 0x0B86 (2950)
• 30°C: 0x0BD6 (3030)

New TIN: Lookup table codes

• Off: 0xAA
• 5°C: 0xDC
• 22°C: 0x86
• 30°C: 0xD6

Integration Guidelines

1. Implement proper LIN transport layer

   • Correct timing (9600 baud)
   • Break detection
   • Checksum validation

2. Handle device discovery

   • Broadcast product identification
   • Query serial numbers
   • Request firmware versions
   • Check error status

3. Map signals to device state

   • Parse appropriate protocol variant (Legacy TIN/New TIN)
   • Convert temperature encodings
   • Track device state changes

4. Implement error recovery

   • Checksum validation with retransmission
   • Device timeout handling
   • Automatic rediscovery on loss

5. Respect timing constraints

   • Frame intervals
   • Response timeouts
   • Periodic status updates

References

Protocol Standards

• LIN Consortium ↗ - Official LIN specifications
• ISO 17987 ↗ - International LIN standard

Related Documentation

• Legacy TIN Protocol Details - Legacy protocol specification
• New TIN Protocol Details - Modern protocol specification
• LIN Protocol Overview - General LIN protocol information

Implementation Resources

• WomoNET Driver Implementation: womonet-drivers/src/tin/
• Protocol Test Data: truma-driver/TRUMA_PROTOCOL.md
• Sample Logs: truma-driver/logs_new.md