IEC 60870-5-104 frame decoder

IEC 60870-5-104 Frame Decoder Online — Free IEC-104 Hex Decoder and Analyzer

The IEC 60870-5-104 (IEC-104) protocol is one of the most widely used communication standards in SCADA (Supervisory Control and Data Acquisition) and substation automation systems. It defines how control centers exchange data with remote terminal units (RTUs) over TCP/IP networks.

If you work with substations, automation testing, or energy systems, you’ve probably encountered raw IEC-104 hex frames. Reading or interpreting these frames manually can be frustrating — that’s why we created this free Online IEC 104 Frame Decoder.

What Is an IEC-104 Decoder?

An IEC-104 decoder is a tool that converts raw hexadecimal data (the binary frame transmitted over TCP) into a human-readable structure showing:

  • APCI: Application Protocol Control Information (I-Frame, S-Frame, U-Frame)
  • ASDU: Application Service Data Unit
  • Type ID (e.g., M_SP_TB_1, C_IC_NA_1)
  • Cause of Transmission (COT)
  • ASDU Address & IOA
  • Timestamp (CP56Time2a format)
  • Object Values and Quality Bits

Instead of using expensive SCADA analysis software or Wireshark filters, this browser-based decoder lets you simply paste hex data and instantly see the decoded fields.

How the Online IEC 104 Frame Decoder Works

Our tool runs entirely in your browser — no uploads, no data leaves your computer.
You simply:

  1. Copy a frame from your network capture or log.
  2. Paste it into the input box.
  3. Click Decode Frame.
  4. The tool automatically parses APCI and ASDU sections and displays:
    • Frame type (I / S / U)
    • Transmission sequence numbers
    • ASDU Type and Description
    • IOA (Information Object Address)
    • Data values, quality bits, and timestamps

You can also download the decoded output as a text file for documentation or testing reports.

Why IEC 60870-5-104 Matters

IEC 104 is the TCP/IP extension of IEC 101, designed for modern networked SCADA systems. It uses the same ASDU structure but transmits over Ethernet, making it faster and easier to integrate with existing IP-based networks.

It’s used in:

  • Power substations for telemetry and control
  • Energy management systems
  • Smart grid communication
  • Water and gas automation
  • Industrial control networks

Because it’s a critical protocol, engineers often need to inspect, debug, and verify frames for interoperability and testing.

Example: Decoding a Frame

Input (raw hex frame):

68 0E 00 00 00 00 64 01 06 00 01 00 00 00 00 14

Decoded Output:

  • Frame Type: I-Frame
  • Send Sequence: 0
  • Receive Sequence: 0
  • ASDU Type: 100 — C_IC_NA_1
  • Cause of Transmission: 6 (ACTIVATION)
  • Objects: 1
  • Asdu Address: 3
  • IO Address: 0
  • Qualifier of interrogation: INTERROGATED_BY_STATION

This kind of quick analysis helps engineers identify whether the message is a spontaneous event, command, or response, and verify the data integrity.

Safe, Fast, and Offline

  • 100% client-side decoding (JavaScript runs locally).
  • Works offline once loaded.
  • No frame data is sent to any server.
  • Ideal for confidential or critical network traces.

Who Uses This IEC-104 Decoder

  • SCADA and Substation Engineers verifying data flows
  • Automation Testers debugging RTU or gateway communication
  • Protocol Developers implementing IEC-104 clients/servers
  • Students and Researchers learning about telecontrol protocols

Whether you’re working on power system automation or protocol stack implementation, this tool provides a reliable and accessible way to interpret IEC-104 traffic.

FAQ

Is this decoder accurate for all ASDU types?

It supports the most common and standardized ASDU types (30–37, 70, 100, 101). Unsupported types are displayed in raw byte form.

Can I use this tool offline?

Yes. Once the page is loaded, decoding happens entirely in your browser without an internet connection.

How is this different from Wireshark?

Wireshark provides low-level capture and protocol analysis, but this tool is lightweight, instant, and focused purely on frame decoding and interpretation.

Conclusion

The Online IEC 60870-5-104 Frame Decoder is the simplest way to decode and analyze IEC-104 frames directly from your browser.
Whether you’re validating RTU messages, testing substation links, or learning the protocol, this tool gives you instant insights into APCI, ASDU, and object data — all without installing any software.

Online IEC 104 Frame Decoder

Try it now: Paste your IEC-104 hex frame and click Decode Frame to see the results instantly.



Support & Feedback

Having trouble decoding a frame, or noticed unexpected output?
We’re here to help!

When contacting support, please include:

  • Decoder tool name (e.g., DNP3 Decoder, Modbus RTU Decoder, IEC-101 Decoder, IEC-104 Decoder)
  • Description of the issue
  • Frame/hex example or error message you encountered
    (copy the frame you tested and any error code shown)

This information helps us quickly identify the issue and improve the tool for everyone.

Contact Support: SCADA Protocols Support Page