Practical guides on ladder logic, structured text, timers, PID control, career paths, and everything else that matters for learning PLC programming.
Latest
Learn a repeatable electrical troubleshooting method: establish the safe energy state, read the schematic, half-split the circuit, interpret voltage patterns, diagnose common motor-control faults, and verify the repair.
We analyzed 10,272 graded ladder logic attempts on our browser PLC simulator. 58% of failures were an output that never turned on, 83% failed within two seconds of clicking Run, and the seal-in circuit was the single hardest concept. Full data study.
A practical, from-zero guide to programming a Universal Robots cobot: the teach pendant and PolyScope, frames and the TCP, waypoints, your first pick-and-place, digital I/O and grippers, safety and protective stops, and how to practise without owning a robot.
The difference between movej, movel and movep is the first thing every Universal Robots programmer has to get right. This guide explains joint vs linear vs process moves, when to use each, blend radius, speed and acceleration, and the classic singularity and overshoot pitfalls — with URScript examples.
URScript is the text-based programming language that runs Universal Robots arms. This guide explains what URScript is, how it relates to PolyScope, the core commands (movej, movel, set_digital_out), variables, functions, and how to start learning it without owning a robot.
Modbus TCP vs Modbus RTU compared: both use the same register model and function codes, but RTU runs on serial RS-485 and TCP runs on Ethernet. This post explains the differences, the MBAP header, how to choose, and how to troubleshoot each variant.
Modbus and CAN bus target different environments. Modbus RTU/TCP is the open industrial register protocol for PLCs and process instruments. CAN bus with CANopen profiles connects embedded motion and drive systems. This post explains the architecture, frame format, and when each protocol fits.
Modbus and DNP3 are both fieldbus protocols used to read RTUs and outstations, but DNP3 was purpose-built for utility SCADA — substations, water treatment, and pipelines — with built-in event reporting, data integrity, and time stamping that Modbus lacks. This post explains the differences and when each protocol is the correct choice.
Diagnose DOL motor starter faults across three zones — contactor coil circuit, overload relay, and control circuit. Multimeter sequence, overload trip checklist, and the half-split from PLC output to contactor A1. Links to wiring lab and related posts.
A systematic 7-step PLC fault-finding method covering multimeter discipline, the half-split method, and how to navigate every fault family — from wiring opens to scan-order bugs. Links to live fault scenarios and wiring fault labs.
PROFINET and EtherCAT both run on Ethernet hardware, but they solve different problems. PROFINET integrates Siemens PLCs with drives and I/O in a standard plant network. EtherCAT delivers microsecond cycle times for high-axis-count servo and CNC applications. This post explains how each works and when to choose one over the other.
SCADA and BMS both supervise equipment and collect data — but they target different environments, use different protocols, and serve different operators. This post explains what each system does, where they overlap, and when a building needs both.
SCADA monitors and controls real-time plant operations. MES manages production orders, schedules, quality, and traceability. They operate at different time horizons and different abstraction levels — but they must talk to each other.
Incremental encoders output a pulse train — you count pulses to track relative position, but lose it on power loss. Absolute encoders output a unique digital word for every shaft position — position is retained across power cycles. Learn when to use each, how to wire them, and how PLCs read both types.
Inductive sensors detect metal only. Capacitive sensors detect anything — metal, plastic, liquid, or powder. Learn how each works, how to wire NPN vs PNP output, and how to pick the right sensor for your application.
Modbus vs PROFIBUS compared: register model vs device profile, RS-485 vs RS-485 DP, speed, diagnostics, vendor support, and when each protocol still makes sense in 2026.
Modbus is a communication protocol. RS-485 is an electrical standard for wiring. They are not the same thing — Modbus RTU runs on RS-485, but so does PROFIBUS. Here is the difference, why it matters, and how to wire it correctly.
A motor starter is a contactor plus an overload relay. This post explains what the overload adds, when you need a full starter vs a bare contactor, how the PLC interlocks with both, and wiring to the control circuit.
Motor starter vs VFD compared: DOL starting vs variable speed, energy savings, starting current, soft start, mechanical wear, and when the extra cost of a VFD is justified.
NPN sensors sink current (pull signal to 0V when active). PNP sensors source current (pull signal to +24V when active). The mismatch between sensor output and PLC input type is the most common discrete wiring mistake. This explains how to read your sensor datasheet, identify your PLC input type, and wire them correctly.
Practical PLC encoder programming examples for Delta, Siemens S7-1200, Allen-Bradley CompactLogix, and Mitsubishi FX. Covers high-speed counter setup, quadrature mode, homing, and position-based output control in each dialect.
PROFINET vs EtherNet/IP: Siemens vs Rockwell, IRT real-time classes vs CIP motion, conformance levels, cable topology, and where Modbus TCP fits when you need something simpler.
SCADA vs DCS compared: integrated platform vs open supervision layer, continuous process vs discrete manufacturing, response time, vendor lock-in, and the convergence happening right now.
SCADA vs HMI: an HMI is a panel for one machine; SCADA is a server supervising dozens of PLCs. This post covers architecture, historian, alarms, scope, and which one a controls engineer actually needs.