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 Port Numbers Explained: UDP 34962/34963/34964, Ethertype 0x8892, and Firewall Configuration

A complete reference for PROFINET ports — covering UDP 34962 (RT Unicast), UDP 34963 (RT Multicast), UDP 34964 (RPC Context Manager), UDP 49152, the Ethertype 0x8892 for cyclic I/O, MRP Ethertype 0x88E3, firewall rules, and Wireshark filters Introduction PROFINET ports are different from every other industrial protocol. Unlike Modbus (port 502), DNP3 (port 20000), or IEC 104 (port… Read More: PROFINET Port Numbers Explained: UDP 34962/34963/34964, Ethertype 0x8892, and Firewall… »

OPC UA Port Number Explained: TCP 4840, Discovery, and Firewall Configuration

OPC UA uses TCP port 4840 by default. This single port carries everything OPC UA does — discovery, session establishment, reading tags, writing values, subscriptions, method calls, and historical data access. Unlike OPC Classic (which used DCOM with dynamic port allocation and was a firewall nightmare), OPC UA uses one well-known port that works cleanly through NAT, proxies,… Read More: OPC UA Port Number Explained: TCP 4840, Discovery, and Firewall… »

Top 10 Free Modbus Simulators

You’re building a SCADA master, configuring a PLC, or bringing up an HMI — but the field devices aren’t there yet. The meters, VFDs, sensors, and I/O modules are still on order, or they’re sitting at a site you can’t reach. A Modbus simulator fills the gap. It runs on your laptop and answers as if it were… Read More: Top 10 Free Modbus Simulators »

IEC 60870-5-104 Type IDs Explained: Complete Reference Guide

Every ASDU (Application Service Data Unit) in IEC 60870-5-104 contains a Type ID — a single byte that defines what kind of data the message carries. It tells the receiving station whether the message contains a single-point indication, a measured value, a command, a counter, or a system message. The Type ID is the first byte of every… Read More: IEC 60870-5-104 Type IDs Explained: Complete Reference Guide »

CIP Object Model Explained: Classes, Instances, Attributes, and Services

Every CIP device — whether it is an Allen-Bradley PLC, a variable frequency drive, a remote I/O module, or a safety controller — organizes its data using the same object model. Understanding this model is the key to configuring, programming, and troubleshooting any CIP-based device. CIP (Common Industrial Protocol) does not use register maps like Modbus. Instead, it… Read More: CIP Object Model Explained: Classes, Instances, Attributes, and Services »

Wireshark for EtherNet/IP: How to Capture and Decode CIP Traffic

EtherNet/IP (Ethernet Industrial Protocol) is the leading industrial Ethernet protocol in North America. It carries CIP (Common Industrial Protocol) messages over standard TCP/IP and UDP/IP. Wireshark fully decodes EtherNet/IP using two dissectors: EtherNet/IP uses two ports: This guide covers how to capture both traffic types, which display filters to use, how to decode CIP services and I/O connections,… Read More: Wireshark for EtherNet/IP: How to Capture and Decode CIP Traffic »

Wireshark for Modbus RTU: How to Capture and Decode Serial RS-485 Traffic

Wireshark is known as an Ethernet protocol analyzer. But it can also capture Modbus RTU traffic over RS-485 serial links — using a free extension called WiresharkSerialAdapter. This is not a built-in feature. Wireshark does not natively capture from COM ports. You need a USB-to-RS-485 adapter connected to the bus as a passive listener, plus the WiresharkSerialAdapter extension… Read More: Wireshark for Modbus RTU: How to Capture and Decode Serial… »

How to Decrypt Encrypted Industrial Protocol Traffic in Wireshark

Industrial protocols are moving to TLS encryption. Modbus/TCP Security uses port 802. IEC 60870-5-104 over TLS uses port 19998. IEC 61850 MMS over TLS uses port 3782. OPC UA encrypts at the application layer. When encryption is enabled, Wireshark shows “Application Data” instead of decoded protocol fields. You can see that packets are flowing, but you cannot read… Read More: How to Decrypt Encrypted Industrial Protocol Traffic in Wireshark »