Zakaria El Intissar

I've spent 13 years in power system automation, electrical protection, and SCADA communication, as an automation and industrial computing engineer. ScadaProtocols.com is where I turn what I've learned on site into plain guides and working tools — so other engineers can decode, analyze, and troubleshoot industrial communication protocols without the guesswork.

Author Archives: Zakaria El Intissar

PROFINET Conformance Classes Explained: CC-A, CC-B, CC-C (IRT), and CC-D (TSN)

PROFINET is one protocol — not three. But it comes in four conformance classes that define what a device can do, how fast it communicates, and what network infrastructure it needs. Engineers often confuse PROFINET RT, PROFINET IRT, and PROFINET IO as separate protocols. They are not. They are all part of PROFINET IO, defined in IEC 61158… Read More: PROFINET Conformance Classes Explained: CC-A, CC-B, CC-C (IRT), and CC-D… »

PROFINET vs EtherNet/IP: Complete Comparison for Industrial Engineers

PROFINET and EtherNet/IP are the two largest Industrial Ethernet protocols in the world. Together they account for over 60% of all new industrial Ethernet nodes installed each year. Both run on standard Ethernet hardware — same cables, same connectors, same switches. But the similarity ends at the physical layer. Above Layer 2, they use completely different protocol stacks,… Read More: PROFINET vs EtherNet/IP: Complete Comparison for Industrial Engineers »

Wireshark for PROFINET: How to Capture and Decode RT, DCP, and IO Traffic

PROFINET traffic does not use TCP/IP for cyclic I/O data. It runs directly on Ethernet Layer 2 with EtherType 0x8892. This means you cannot capture it with a TCP port filter — you need to capture all Ethernet traffic on the interface and then filter in Wireshark. Wireshark fully decodes PROFINET using several dissectors: This guide covers how… Read More: Wireshark for PROFINET: How to Capture and Decode RT, DCP,… »

Wireshark for MQTT: How to Capture and Decode Industrial IoT Traffic

MQTT (MQ Telemetry Transport) is the most widely used protocol in industrial IoT. It connects sensors, PLCs, gateways, and edge devices to cloud platforms and SCADA historians using a lightweight publish/subscribe model over TCP. Wireshark fully decodes MQTT — every CONNECT, PUBLISH, SUBSCRIBE, and DISCONNECT message, including topic names, QoS levels, payloads, and client IDs — all in… Read More: Wireshark for MQTT: How to Capture and Decode Industrial IoT… »

Wireshark for OPC UA: How to Capture and Decode Client/Server Traffic

OPC UA (Unified Architecture) is the leading platform-independent protocol for industrial data exchange. It connects SCADA systems, MES platforms, HMI panels, historians, and cloud gateways to PLCs, DCS controllers, and edge devices. OPC UA uses the OPC Binary protocol over TCP on port 4840 (IANA registered as “opc.tcp”). Wireshark decodes every OPC UA service — OpenSecureChannel, CreateSession, Browse,… Read More: Wireshark for OPC UA: How to Capture and Decode Client/Server… »

Wireshark for DNP3: How to Capture, Filter, and Troubleshoot

DNP3 (Distributed Network Protocol 3.0) is the dominant SCADA protocol in North America for electric utilities, water systems, and oil and gas. It runs over TCP or UDP on port 20000. Wireshark fully decodes DNP3 — data link layer, transport layer, and application layer. You can see every function code, object group, data point index, quality flag, and… Read More: Wireshark for DNP3: How to Capture, Filter, and Troubleshoot »

Wireshark for Modbus TCP: How to Capture, Filter, and Troubleshoot

Modbus TCP is one of the easiest protocols to analyze in Wireshark. It runs on TCP port 502, uses a simple request/response pattern, and Wireshark decodes every field — MBAP header, function code, register addresses, and data values — in plain text. But engineers still struggle with three things: finding the right display filters, understanding what a healthy… Read More: Wireshark for Modbus TCP: How to Capture, Filter, and Troubleshoot »

How to Configure Modbus TCP on Allen-Bradley CompactLogix (Studio 5000 Step-by-Step)

Allen-Bradley CompactLogix and ControlLogix PLCs do not support Modbus TCP natively. Their primary protocol is EtherNet/IP. But in many industrial systems, you need to communicate with Modbus TCP devices — energy meters, VFDs, third-party sensors, or legacy equipment. Rockwell Automation provides a free solution: Modbus TCP Add-On Instructions (AOIs). These are pre-built function blocks you import into Studio… Read More: How to Configure Modbus TCP on Allen-Bradley CompactLogix (Studio 5000… »

PROFINET GSD/GSDML Files Explained: What They Are and How to Use Them

Every PROFINET device comes with a GSD file. Without it, your PLC does not know the device exists. It cannot configure modules, exchange I/O data, or read diagnostics. GSD stands for General Station Description. In PROFINET, GSD files are written in XML format. The language used is called GSDML — General Station Description Markup Language. The file extension… Read More: PROFINET GSD/GSDML Files Explained: What They Are and How to… »