Terminology » ISO-TP Frame Analysis & Automotive Diagnostic Software

ISO-TP Frame Analysis & Automotive Diagnostic Software

automotive iso-tp frame protocol analyzer tool

Introduction : The ISO‑TP (ISO 15765-2) is a transport layer protocol over CAN (and CAN-FD) that enables messages longer than a single CAN frame. It also handles synchronization between the sending and receiving nodes to ensure the packets can be interpreted and received correctly

ISO-TP Frame Structure

CAN-TP supports different frame types to manage portions of the message to send over CAN/CAN-FD. These frames are differentiated based on their unique value in PCI high nibble position.

Single Frame (SF) : 0
First Frame (FF) : 1
Consecutive Frame (CF) : 2
Flow Control (FC) Frame : 3

CAN TP Frame Types

Single Frame (SF)

Used when the entire diagnostic message fits in one CAN frame (data length 1–7 bytes).

Field (Byte position)	Size	Purpose/Description
SF PCI (Byte 0)	1 byte	4-bit type + 4-bit payload length
Data (Byte 1-7)	0-7 bytes	Application payload

First Frame (FF)

Used when transmitting messages longer than 7 bytes.

Field	Size	Purpose/Description
FF PCI (Byte 0-1)	2 bytes	Frame type + total message length
Data (Byte 2-7)	6 bytes	First part of segmented payload

Consecutive Frame (CF)

Carries the remainder of data after an FF.

Field	Size	Purpose/Description
CF PCI (Byte-0)	1 Byte	Type + sequence number (0–15)
Data (Byte 1-7)	Up to 7 bytes	Payload continuation

Flow Control (FC) Frame

Sent by the receiver to control the sender’s transmission rate.

Field	Size	Purpose/Description
FC PCI (Byte 0)	1 byte	Type + Flow Status
Block Size (Byte 1)	1 byte	#CFs allowed before next FC
STmin (Byte 2)	1 byte	Minimum delay between frames
Reserved (Byte 3-7)	5 bytes	Must be 0

Flow Status (FS) Values:

FS Value	Meaning
0	Continue to Send (CTS)
1	Wait (WT)
2	Overflow/abort (OVFLW)

ISO-TP Data logger tool

Manufacturers	Products/Description
RVector Informatik	Very prominent in automotive toolchains. Their tools like CANoe, CANalyzer, etc., support higher-layer protocols including ISO-TP / UDS.
CSS Electronics	The data loggers support CAN, CAN-FD and protocols like UDS (which sits on ISO-TP). Example : CANedge2 Logger supports 2 × CAN + SD logging, high throughput, ideal for capturing multi-frame ISO-TP traffic.
PEAK-System Technik GmbH	They provide ISO-TP APIs (PCAN-ISO-TP) and CAN interfaces.
Softing Automotive	provides diagnostic interfaces (VCIs) and hardware for CAN / UDS / ISO-TP.

Summary: ISO-TP diagnostic software enables detailed analysis of how large diagnostic or data blocks are fragmented, transmitted and reassembled over CAN networks. It offers critical insights into diagnostic communication and transport layer behavior of ECUs.