ARXML file example, and how to read one

What is inside an ARXML file

Every ARXML file has one root element, <AUTOSAR>, whose namespace names the schema: http://autosar.org/schema/r4.0 for AUTOSAR 4, with the exact release in xsi:schemaLocation (AUTOSAR_00051.xsd in our example). Inside, AR-PACKAGE elements nest like folders, and each holds ELEMENTS.

Each element has a SHORT-NAME. The path of short names from the root is its AR-PATH, such as /NovairSample/Signals/DoorLockSts_FL: that is how one element refers to another (a …-REF element with a DEST attribute), and how a tool finds the same element in two versions of a file, whatever the order.

• I-SIGNAL: a signal, with its length, initial value and computation method (factor, offset, unit).
• I-SIGNAL-I-PDU: a PDU, with its length and the list of its signals, each at a start position and in a byte order.
• CAN-FRAME, LIN-FRAME, FLEXRAY-FRAME: the frame and its PDUs; the frame triggering on a cluster gives its ID.
• Ports, interfaces and software components: P-PORT-PROTOTYPE, R-PORT-PROTOTYPE, SENDER-RECEIVER-INTERFACE, APPLICATION-SW-COMPONENT-TYPE.

A signal

The sample extracts shipped with ARXML Compare describe a body controller ECU (written by Novair; no real vehicle). Here is the signal DoorLockSts_FL, novair-sample-body-ecu_v1.arxml, line 227:

<I-SIGNAL UUID="u-00000014">
  <SHORT-NAME>DoorLockSts_FL</SHORT-NAME>
  <INIT-VALUE>
    <NUMERICAL-VALUE-SPECIFICATION>
      <VALUE>1</VALUE>
    </NUMERICAL-VALUE-SPECIFICATION>
  </INIT-VALUE>
  <LENGTH>2</LENGTH>
  <NETWORK-REPRESENTATION-PROPS>
    <SW-DATA-DEF-PROPS-VARIANTS>
      <SW-DATA-DEF-PROPS-CONDITIONAL>
        <COMPU-METHOD-REF DEST="COMPU-METHOD">/NovairSample/CompuMethods/CM_Text</COMPU-METHOD-REF>
      </SW-DATA-DEF-PROPS-CONDITIONAL>
    </SW-DATA-DEF-PROPS-VARIANTS>
  </NETWORK-REPRESENTATION-PROPS>
</I-SIGNAL>

LENGTH is in bits (2 bits here). INIT-VALUE is the value sent before the first real one. The COMPU-METHOD-REF points, by AR-PATH, to the computation method that turns raw values into physical values or text. The UUID is an identifier that many tools regenerate at each export: it says nothing about the signal.

Where the signal sits in its PDU

The position of a signal is not written in the signal but in a mapping inside the PDU. Here is the mapping of DoorLockSts_FL in PDU BCM_Status_01, line 2248:

<I-SIGNAL-TO-I-PDU-MAPPING UUID="u-00000096">
  <SHORT-NAME>DoorLockSts_FL_ISM</SHORT-NAME>
  <I-SIGNAL-REF DEST="I-SIGNAL">/NovairSample/Signals/DoorLockSts_FL</I-SIGNAL-REF>
  <PACKING-BYTE-ORDER>MOST-SIGNIFICANT-BYTE-LAST</PACKING-BYTE-ORDER>
  <START-POSITION>12</START-POSITION>
  <TRANSFER-PROPERTY>TRIGGERED-ON-CHANGE</TRANSFER-PROPERTY>
</I-SIGNAL-TO-I-PDU-MAPPING>

START-POSITION is the start bit, PACKING-BYTE-ORDER the byte order (MOST-SIGNIFICANT-BYTE-LAST is little endian, Intel; MOST-SIGNIFICANT-BYTE-FIRST is big endian, Motorola), and TRANSFER-PROPERTY says whether a change of the signal triggers a transmission.

The frame and its ID

The CAN ID is written on the frame triggering of the cluster, in decimal, line 3638:

<CAN-FRAME-TRIGGERING UUID="u-00000146">
  <SHORT-NAME>FT_FR_BCM_Lights_01</SHORT-NAME>
  <FRAME-PORT-REFS>
    <FRAME-PORT-REF DEST="FRAME-PORT">/NovairSample/Ecus/DCU_FL/Conn_DCU_FL_CAN_Body/FP_FT_FR_BCM_Lights_01_OUT</FRAME-PORT-REF>
    <FRAME-PORT-REF DEST="FRAME-PORT">/NovairSample/Ecus/DCU_FR/Conn_DCU_FR_CAN_Body/FP_FT_FR_BCM_Lights_01_IN</FRAME-PORT-REF>
    <FRAME-PORT-REF DEST="FRAME-PORT">/NovairSample/Ecus/ESP/Conn_ESP_CAN_Body/FP_FT_FR_BCM_Lights_01_IN</FRAME-PORT-REF>
  </FRAME-PORT-REFS>
  <FRAME-REF DEST="CAN-FRAME">/NovairSample/Frames/FR_BCM_Lights_01</FRAME-REF>
  <CAN-ADDRESSING-MODE>STANDARD</CAN-ADDRESSING-MODE>
  <IDENTIFIER>673</IDENTIFIER>
</CAN-FRAME-TRIGGERING>

673 in decimal is 0x2A1. The FRAME-PORT-REFS list the ECUs that send (…_OUT) and receive (…_IN) the frame.

How to open and read an ARXML file

An ARXML file is plain XML, so any text editor opens it, but a real extract runs to tens of thousands of lines, and the answer to a simple question (which signals are in this PDU, at which start bit?) is spread over several elements. A reader that follows the references does the work for you.

1. Install ARXML Compare, free, from the VS Code Marketplace.
2. Right-click an .arxml file in the Explorer, or use the “Open in ARXML Compare” button in the editor title.
3. The tree shows the packages and elements by SHORT-NAME. Type the start of an AR-PATH to jump to an element, and see what it refers to and what refers to it.
4. The tables show the communication matrix: each signal with its PDU, frame, ID, start bit, length, byte order, initial value, factor, offset, unit and senders. Copy a table as tab-separated text into a spreadsheet.

No VS Code at hand? The free online tool compares two ARXML files in your browser and counts the changes by domain: https://arxml-compare.novair.app/tools/compare-arxml-online/

Errors you may meet when opening an ARXML file

These are the messages ARXML Compare shows, produced by its own code from the test files it is checked against:

• The export was cut off or edited by hand: “malformed.arxml is not well-formed XML at line 290, column 17: expected end tag </SW-DATA-DEF-PROPS-VARIANTS> (opened at line 286), found </SW-DATA-DEF-PROPS-VARIANTS-BROKEN>. Elements read before this point are shown. Fix the file or ask for a new export.”
• An XML file that is not AUTOSAR: “not-autosar.xml is not an AUTOSAR file: its root element is <project>, not <AUTOSAR>.”
• A file saved in a mainframe or legacy encoding: “ibm037.arxml uses the IBM037 encoding, which ARXML Compare does not read. Save it as UTF-8.”
• An empty file: “empty.arxml is empty.”
• A folder with no .arxml file: “extract_2026-11 contains no .arxml file.”

A file cut off in the middle (a failed export, a truncated attachment) is the most common case: the elements read before the error are shown, and the line and column tell you where to look.

Frequently asked questions