Service Interaction Protocol

Transfer Data

0x36

Protocol Identifier

The TransferData service is used to transfer data blocks between the tester and ECU as part of a download or upload sequence initiated by RequestDownload (0x34) or RequestUpload (0x35).

Overview

ISO 14229-1

TransferData is the middle step in the download/upload sequence. Each request contains a block sequence counter that ensures data integrity. The maximum block size is determined by the preceding RequestDownload or RequestUpload response.

Interactions with Other SIDs

Prerequisites & Dependencies

0x34RequestDownload must be active for tester→ECU transfers
0x35RequestUpload must be active for ECU→tester transfers
0x37RequestTransferExit completes the sequence

Data Direction

After 0x34 (Download)

Tester sends data IN request

After 0x35 (Upload)

ECU sends data IN response

Message Format

Request Format (Download)

Byte	Field	Value	Description
0	SID	0x36	Transfer Data
1	blockSequenceCounter	0x01-0xFF	Block number (starts at 0x01, wraps at 0xFF)
2-N	transferRequestParameterRecord	Variable	Data block (max size from 0x34/0x35 response)

Response Format (Download)

Byte	Field	Value	Description
0	Response SID	0x76	Positive Response
1	blockSequenceCounter	Echo	Echo of block number

Response Format (Upload)

Byte	Field	Value	Description
0	Response SID	0x76	Positive Response
1	blockSequenceCounter	Echo	Echo of block number
2-N	transferResponseParameterRecord	Variable	Data block from ECU

Block Sequence Counter

Counter Behavior

Start: First block is always 0x01
Increment: Each subsequent block increments by 1
Wrap: After 0xFF, wraps to 0x00 (not 0x01)
Validation: ECU rejects out-of-sequence blocks

Sequence: 01 → 02 → 03 → … → FE → FF → 00 → 01 → 02 → …

TX/RX Examples

Download Data Blocks

tx_packet

Block 1

36 01 [512 bytes of firmware]

> First data block

rx_packet

Response

76 01

> Block 1 received

tx_packet

Block 2

36 02 [512 bytes of firmware]

> Second data block

rx_packet

Response

76 02

> Block 2 received

✓

Continue until all data transferred

Upload Data Blocks

tx_packet

Request Block 1

36 01

> Request first block

rx_packet

Response

76 01 [512 bytes from ECU]

> Block 1 data

tx_packet

Request Block 2

36 02

> Request second block

rx_packet

Response

76 02 [512 bytes from ECU]

> Block 2 data

✓

ECU sends data in response

Wrong Block Sequence

tx_packet

Block 3 (skipped 2)

36 03 [data]

> Out of sequence

rx_packet

Error Response

7F 36 73

> Wrong block sequence counter

Error

Blocks must be sent in order

No Active Transfer

tx_packet

Request

36 01 [data]

> Without 0x34/0x35 first

rx_packet

Error Response

7F 36 24

> Request sequence error

Error

Must call RequestDownload or RequestUpload first

UML Sequence Diagrams

Multiple Block Download

Download 2KB in 512-byte Blocks

12 steps

Tester

ECU

Anticipated Behavior

warning _entry

Block Size Limit: Never exceed the maxNumberOfBlockLength returned by 0x34/0x35. The last block may be smaller if the total size doesn’t divide evenly.

info _entry

Response Pending: Flash programming may take time. The ECU may send NRC 0x78 (Response Pending) while writing data to flash memory.

Negative Response Codes (NRCs)

NRC	Name	Description
0x13	Incorrect Message Length	Block too large or missing data
0x24	Request Sequence Error	No active download/upload (missing 0x34/0x35)
0x71	Transfer Data Suspended	Transfer interrupted, must restart
0x72	General Programming Failure	Flash write error
0x73	Wrong Block Sequence Counter	Out-of-order block number
0x78	Response Pending	Flash programming in progress (NOT an error)