Decode, analyze, and troubleshoot IEC 60870-5-101 frames directly in your browser — with full originator support and automatic frame detection of Balanced / Unbalanced communication modes.
Our free online tool makes it easy for SCADA engineers, testers, and automation professionals to interpret IEC-101 frames (fixed and variable length) without needing custom software or protocol analyzers.
What Is IEC 60870-5-101?
The IEC 60870-5-101 protocol (often shortened to IEC 101) is a telecontrol standard defined by the International Electrotechnical Commission (IEC).
It’s widely used in power systems, SCADA networks, and industrial automation to exchange data between control centers and remote terminal units (RTUs).
IEC 101 defines both the link layer and application layer for serial communication. It supports balanced and unbalanced modes, and uses two main frame types:
- Fixed-length frames (0x10 … 0x16) for simple commands or acknowledgments
- Variable-length frames (0x68 … 0x16) for application data (ASDUs)
About the IEC 60870-5-101 Decoder
Our Universal Decoder (Originator Support) lets you paste any raw IEC-101 hex frame and get a complete, human-readable breakdown of the message.
Whether you’re decoding link-layer control fields or inspecting ASDU contents, this tool gives you clarity in seconds.
Key Features
- Automatic frame detection — recognizes fixed vs variable length automatically
- Checksum validation — confirms frame integrity
- Originator address decoding — supports systems that use originator addressing
- Cause of Transmission (COT) mapping — instantly explains whether a message is spontaneous, cyclic, or command-related
- Readable ASDU interpretation — shows IOA, value, quality, and timestamp
- Browser-based & secure — no installation, no data leaves your device
Why Use a Dedicated Decoder?
Parsing IEC 101 manually is tedious and error-prone. Frames differ in address sizes, COT formats, and ASDU structures depending on implementation.
Our tool automatically tests combinations of:
- Link address sizes (1–2 bytes)
- ASDU addresses (1–2 bytes)
- COT sizes (1–2 bytes)
- IOA sizes (1–3 bytes)
It automatically determines which combination works and decodes accordingly — a feature missing in most decoders.
How to Use the IEC 60870-5-101 Decoder (Step-By-Step)
- Copy your raw hex frame from a serial capture, RTU log, or SCADA trace.
Example:68 0E 0E 68 08 01 00 06 00 01 00 00 00 14 00 00 16 - Paste it into the decoder’s input box.
- Click “Decode Frame”.
- Review the output:
- Link layer details (PRM, FCB, FCV, direction, function code)
- ASDU type and description (e.g., M_SP_TB_1 – Single Point Information with Time Tag)
- Cause of transmission (e.g., spontaneous)
- Information objects (IOA, Value, Quality, Timestamp)
- Checksum validation status
Within seconds, you’ll know exactly what the message represents.
Use Cases for SCADA & Automation Professionals
- Protocol debugging: Quickly validate IEC 101 messages captured from serial lines
- RTU integration: Verify correct addressing and data types during system setup
- Training & education: Help students understand IEC telecontrol message flow
- Compliance testing: Cross-check ASDU formats with IEC standard definitions
Why Engineers Love This Tool
“The best IEC 101 decoder I’ve used — auto-detects field sizes and gives clear results instantly.”
— Electrical Engineer, Smart Grid Integrator
By saving hours of manual parsing and troubleshooting, the IEC 60870-5-101 Universal Decoder has become an indispensable companion for engineers worldwide.
Try the IEC 60870-5-101 Decoder Online
Stop wasting time deciphering hex dumps by hand.
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