300+ SCADA Protocol Articles & Guides
Deep dives on Modbus, DNP3, IEC 60870-5-101/104, IEC 61850, OPC UA, Profinet, MQTT, IEC 62443, and substation automation — written for practicing engineers.
SCADA and ICS: The Difference and How They Fit Together
SCADA and ICS are not the same thing: SCADA is one type of ICS. See how SCADA, DCS, and PLC systems fit inside ICS and OT, per NIST and IEC definitions.
Modbus Unit Identifier Explained: Unit ID by Scenario
Modbus Unit Identifier (Unit ID) explained by scenario: direct TCP devices, RTU gateways, multi-port gateways. Value ranges, common defaults, troubleshooting.
Modbus Broadcast Function Codes: Address 0 Explained
Modbus broadcast on address 0: which function codes support it, how serial and TCP differ, turnaround timing, gateway behavior, and when to actually use it.
Modbus Client-Server vs Master-Slave Terminology
Modbus client-server vs master-slave: the 2020 terminology change explained. What stays the same, translation table, and how to read mixed-terminology docs.
Modbus TCP MBAP Header Explained: 7 Bytes Byte by Byte
Modbus TCP MBAP header decoded byte by byte: Transaction ID, Protocol ID, Length, and Unit ID, with a real hex dump, network byte order, and common mistakes.
Modbus TCP Security Explained: TLS on Port 802
Modbus TCP Security explained: TLS on port 802, X.509 certificates, role-based access control, deployment alongside port 502, cipher suites, real setup.
Modbus Byte Order and Word Order: Fix Your 32-Bit Values
Modbus byte order and word order decoded: ABCD, CDAB, BADC, and DCBA. Fix reversed floats and byte-swapped longs, with a five-minute test and vendor defaults.
Allen-Bradley EtherNet/IP: CIP Configuration Guide
Allen-Bradley EtherNet/IP setup on ControlLogix and CompactLogix: implicit vs explicit messaging, Generic Ethernet Module, MSG instructions, and fault codes.
Free FTP Clients: Which One Fits the Job You Do
FileZilla, WinSCP, curl, lftp, Cyberduck — all free. Which FTP client fits your job, which support SFTP, and which to use for scripts and field work.
FTP Explained: How File Transfer Protocol Works
How FTP really works: the two-connection model, active vs passive mode, commands, reply codes, and why FTP fails security audits. Plus FTP vs FTPS vs SFTP.
MQTT 5 Maximum Packet Size Explained: Property 0x27
MQTT 5 Maximum Packet Size (Property 0x27): declare per-connection packet limits, Reason Code 0x95, tuning for embedded to high-throughput, worked examples.
MQTT 5 Request Response Pattern Explained: RPC Over MQTT
MQTT 5 request/response pattern: Response Topic (0x08), Correlation Data (0x09), Request Response Information (0x19), Response Information (0x1A), RPC patterns.
MQTT 5 Correlation Data Explained: Request/Response Pattern
MQTT 5 Correlation Data (Property 0x09) and Response Topic (0x08): how request/response messaging works in MQTT 5, patterns, examples, common mistakes.
MQTT 5 Topic Aliases Explained: Per-Connection Bandwidth
MQTT 5 Topic Aliases: Property 0x23, Topic Alias Maximum 0x22, per-connection state, bandwidth reduction, Reason Code 0x94, mapping rules, examples.
CIP Security Explained: TLS, X.509, and OT Cybersecurity
CIP Security architecture: TLS for TCP 44818, DTLS for UDP 2222, X.509 certificates, device authentication, trust models, EST provisioning, IEC 62443 alignment.
EtherNet/IP vs Modbus TCP: Complete Comparison Guide
EtherNet/IP vs Modbus TCP: detailed comparison of data models, performance, ports, security, deployment scenarios. When to choose which protocol.
Enhanced Authentication in MQTT 5 Explained
MQTT 5 Enhanced Authentication: AUTH packet, SASL flows, SCRAM, OAUTHBEARER, GSSAPI, re-authentication. Multi-step challenge-response auth in MQTT 5.0.
MQTT 5 Flow Control Explained: Receive Maximum
MQTT 5 Flow Control: Receive Maximum (Property 0x21), Maximum Packet Size, in-flight QoS 1 and QoS 2 limits, Reason Code 0x93, tuning, examples.