SCADA Protocols. Simplified.
Practical guides, free decoders, and tools for SCADA and industrial protocols, including DNP3, IEC 60870-5, IEC 61850, Modbus, OPC UA, MQTT, and more.
Decode frames right in your browser
No installation, no sign-up. Paste a hex dump, get a clean human-readable breakdown for the most common SCADA protocols.
DNP3 Frame Decoder
Paste raw DNP3 hex frames and decode link-layer headers, transport, function codes, and CRCs with human-readable breakdowns.
Modbus Frame Decoder / Encoder
Decode or build Modbus RTU/TCP frames: function codes, registers, coils, MBAP header, and CRC/LRC validation online.
IEC 101 Frame Decoder
Interpret IEC 60870-5-101 serial frames: link addresses, control fields, function codes, and ASDU type IDs with causes.
IEC 104 Frame Decoder
Decode IEC 60870-5-104 APDUs, APCI start bytes, I/S/U formats, and ASDU payloads with time-tagged value inspection.
IEC 103 Frame Decoder
Parse IEC 60870-5-103 protection equipment frames: ASDU 1–10, generic services, disturbance data, and type-specific events.
Recent articles
Deep technical dives on protocol details, field troubleshooting, interoperability pitfalls, and secure SCADA architectures.
CANopen Explained: Object Dictionary, PDO, SDO, NMT
CANopen explained: the object dictionary at the centre of every device, SDO vs PDO, expedited and normal transfers, heartbeat and EMCY, and how device profiles work.
CANopen vs CAN Bus: What's the Difference? (Explained)
CANopen vs CAN bus explained: they are not competitors but two layers of the same stack. What CAN provides, what CANopen adds, and how to tell which one a device speaks.
HART Protocol Explained: Digital Data on a 4-20 mA Loop
HART protocol explained: how digital signalling rides on a 4-20 mA loop, dynamic variables, universal commands, burst mode, multidrop, and where WirelessHART fits.
CAN FD Explained: Bigger Frames, Faster Data Phase
CAN FD explained: how the data phase switches to a faster bit rate, 64-byte payloads, BRS and ESI bits, the compatibility problem with classic controllers, and CAN FD light.
DeviceNet Explained: CAN, CIP, Power and Wiring
DeviceNet explained: how it layers CIP over CAN, the four message groups, MAC IDs and duplicate detection, bus power limits, cable types, and speed vs distance limits.
CAN Bus Protocol Explained: Frames, Arbitration, Errors
CAN bus protocol explained from the standards: dominant and recessive bits, identifier arbitration, the five frame formats, error states and bus-off, CAN FD and CAN XL.
Built for electrical and automation engineers. Not marketers.
Everything on this site is written from 12+ years of hands-on substation automation and control systems experience.
Deep Protocol Analysis
Frame-by-frame breakdowns of DNP3, IEC 104, Modbus and more — written by a senior power systems engineer.
Production-Grade Decoders
Five battle-tested online decoders. Paste raw hex, get clean ASDU, APDU and transport-layer interpretation.
Engineer-to-Engineer
No fluff, no clickbait. Real protocols, real field scenarios, real troubleshooting tips from 12+ years in substations.
Explore protocol references
Structured overviews, message structure diagrams, ASDU tables, and common gotchas for twelve widely-used protocols.