Inspect raw frames
Review timestamps, CAN channels, frame IDs and payload bytes without a DBC. This helps confirm that the event and message you need were recorded.
MF4 viewer online for CAN and CAN FD logs
Open a recorded .mf4 CAN bus log in your browser to inspect frames, channels, IDs and payload bytes. Add a matching DBC when you need named signals and plots. Local opening does not upload the file.
Drop an MF4 CAN log here
Choose a .mf4 CAN bus log up to 150 MiB. The sample demonstrates the workbench with a synthetic log; it is not an MF4 compatibility test.
What you can inspect in an MF4 CAN log
Use raw frames to verify the recording first. Decode signals only after checking the DBC and channel mapping.
Find the relevant messages
Filter the trace by channel and frame ID to isolate the traffic around an event before decoding it.
Check the source bytes
Open a frame to compare its payload with the DBC definition when a decoded value needs verification.
Map your DBC
Link the DBC for the recorded network to each channel. Check a known message before trusting physical values or signal plots.
MF4 viewer workflow: frames, DBC signals and export
An MF4 file can answer different questions depending on whether you have its DBC and what result you need to take away.
Inspect MF4 frames without a DBC
Start in the Frames view to confirm the recording contains the expected CAN channel and message ID. Timestamps and raw payload bytes are useful for checking whether a message appeared near an event, even if the signal definitions are unavailable.
Decode MF4 CAN signals with the right DBC
A DBC supplies signal names, bit positions, scaling and units; the MF4 alone does not supply those definitions. Map the DBC to the channel it describes. A wrong DBC revision can produce missing signals or plausible but incorrect values, so verify one known frame before using a plot.
Export the result you actually need
The workbench can export decoded signal CSV for inspection in a spreadsheet or script. If the next step expects a .mat file or a separate conversion run, use the dedicated MF4 converter. Decoded exports are interpretations of the source recording; keep the original MF4 for later checks.
Need a MAT or CSV file? Use the MF4 converter.How to open an MF4 file and decode it with a DBC
Start with the original recording, check its CAN frames, then add a DBC only for the signals you need.
Open the recording
Choose a .mf4 file from your computer. The browser reads supported CAN bus logging groups and opens the analysis workbench; no account is needed for this local step.
Add a matching DBC
Check the detected channels and frame IDs first. To decode signals, load the DBC from the recorded vehicle and software version, then map it to the corresponding CAN channel.
Inspect and export
Inspect the raw frame beside a decoded value. If the signal looks wrong, check the DBC version, message ID, byte order and channel mapping before exporting results.
MF4 viewer compatibility and file limits
MF4 is a container format. This viewer reads supported CAN bus logging structures rather than every measurement layout stored in an MDF4 file.
Supported CAN bus logging records
The reader looks for CAN_DataFrame, CAN_RemoteFrame and CAN_ErrorFrame bus logging groups. Supported records expose frame time, channel, ID and data; CAN FD payloads can be inspected when present.
Layouts this viewer may reject
An unfinalized MF4, a data block or compression method this reader does not implement, or a file with no recognized CAN bus frames can fail to open. A measurement-only MF4 is not converted into CAN frames.
150 MiB local file limit
The local workbench accepts one log up to 150 MiB. A file below that limit can still need more memory after decompression, so performance depends on the recording and your device.
MF4 troubleshooting: frames, channels and signals
Check the earliest failing step before changing the DBC or exporting data.
The MF4 has no recognized CAN frames
Confirm that the file is a finalized MDF4 recording with CAN bus logging groups, rather than a measurement-only file. A parser error about a block or compression method means this browser reader cannot handle that layout; renaming the extension will not change the contents.
Frames appear, but no decoded signals appear
Look at a raw frame ID and its channel, then check whether the mapped DBC defines that ID. A DBC from another vehicle network or software revision may leave frames visible but produce no signal names.
A signal value looks wrong
Compare the raw payload with the DBC's bit position, byte order, signedness, factor and offset. Also confirm that the DBC is mapped to the channel that recorded the frame before trusting the graph.
Where MF4 data goes when you use this viewer
The local viewing action and optional account features have different data flows.
Opening an MF4 locally
Choosing or dropping a local MF4 reads and decodes it in your browser. Opening it this way does not upload the file bytes for server-side parsing.
Cloud projects and the AI assistant
Saving a cloud project sends analysis settings and metadata. Uploading a log to cloud storage is a separate selection. When you use the AI assistant, your message and limited analysis context go to the service and AI provider.
Read the data-flow details.MF4 viewer FAQ
Do I need a DBC to open an MF4?
No. You can inspect supported raw CAN frames without a DBC. A matching DBC is needed to decode named physical signals.
Is my MF4 uploaded?
Opening the file locally parses it in your browser without uploading its bytes. Cloud file upload and the AI assistant are separate optional actions.
Can this open every MF4 file?
No. This viewer targets CAN bus logging groups. Other MDF4 measurement layouts, unfinalized files, or unsupported compression and data blocks may not open.
Can I convert MF4 to MAT or CSV?
Yes. The workbench exports decoded signal CSV. For separate MAT or CSV output, use the MF4 to MAT/CSV converter and map a matching DBC to the recorded channels.
Why does my MF4 open with no signals?
Raw CAN frames can appear without named signals. Check that the DBC matches the recorded network and software version, that it is mapped to the correct channel, and that it defines the frame IDs in the file.
Can I view a large MF4 file online?
The local workbench accepts an MF4 up to 150 MiB per file. Decoding and decompression also use your device's memory. For a larger capture, split or process it with another workflow before trying to open it here.
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