PLC and Automation Guides, Page 4

PLC Troubleshooting Interview Questions: Real Answers

Preparing for a PLC troubleshooting interview? These 20 real questions cover scan cycle faults, I/O failures, comms errors and analog issues, with field-tested answers.

Jul 17, 2026 · 13 min read

Types of PLC Modules: I/O, Comms and More

From discrete I/O cards to specialty motion modules, learn what every type of PLC module does, how they differ, and when to use each one.

Jul 17, 2026 · 11 min read

Ladder Logic Interview Questions: Real Answers

Preparing for a PLC role? These ladder logic interview questions cover contacts, coils, timers, counters, latching, scan cycle, and common gotchas interviewers love to probe.

Jul 16, 2026 · 13 min read

PLC Pump Station Exercise: Ladder Logic

Build a realistic two-pump station in ladder logic: level-based start/stop, duty/standby alternation, run-confirm fault detection, and a hand-off-auto selector.

Jul 15, 2026 · 7 min read

Car Wash PLC Exercise: Full Ladder Logic

A step-by-step PLC ladder logic exercise for an automated car wash: inputs, outputs, sequence states, interlocks, and the timing tricks you need to get it right.

Jul 15, 2026 · 6 min read

PLC Scan Cycle Problems: Logic and Timing Faults

Scan cycle timing is behind more PLC logic faults than most engineers realise. Here is how to diagnose watchdog trips, missed pulses and race conditions in real programs.

Jul 15, 2026 · 10 min read

PLC I/O Fault Diagnosis with a Multimeter

Learn how to use a multimeter to diagnose PLC input and output faults fast: voltage checks, continuity tests, load verification and the common mistakes that waste hours.

Jul 14, 2026 · 9 min read

PLC Troubleshooting with Online Monitoring

Online monitoring turns a running PLC into its own diagnostic tool. Learn the exact steps to isolate faults using live rung status, force tables and tag cross-reference.

Jul 14, 2026 · 8 min read

Electric Actuator Sizing: Torque, Thrust and Duty

Size electric actuators correctly by calculating required torque or thrust, applying a safety factor, and matching duty cycle. Avoid the common mistakes that burn out actuators.

Jul 14, 2026 · 8 min read

Emergency Stop Circuit Wiring: Categories Explained

Learn how emergency stop circuits are wired, what ISO 13850 categories mean in practice, and how dual-channel monitoring actually works on real hardware.

Jul 13, 2026 · 10 min read

Control Panel Wire Routing and Segregation

Mixing power and signal wires in a control panel causes noise, spurious faults and headaches. Here is how to route and segregate them correctly.

Jul 13, 2026 · 8 min read

24 VDC Power Supply Sizing for Control Panels

Learn how to size a 24 VDC power supply for a PLC control panel: load tallying, derating, inrush, redundancy options and real worked examples.

Jul 13, 2026 · 10 min read

Shielding Analog Signal Cables in PLC Panels

Analog noise in PLC panels usually traces back to wrong shield grounding. Here's the exact technique, the common mistakes and the real-world numbers that matter.

Jul 12, 2026 · 8 min read

Cable Shield Grounding: One End or Both?

Shield grounding is one of the most argued topics in panel design. Here is the engineering behind single-point vs both-end termination, with real rules for 4-20 mA, thermocouples and fieldbus.

Jul 12, 2026 · 8 min read

4-20 mA Scaling in a PLC: ST and Ladder Code

Turn a raw 0-32767 analog count into bar, °C or m³/h. Full 4-20 mA scaling walkthrough with structured text and ladder code for Studio 5000 and TIA Portal.

Jul 12, 2026 · 7 min read

Servo Drive Tuning: PID Gains Explained

Servo drive tuning mystifies a lot of engineers. Here is what P, I and D gains actually control in a servo loop, with real numbers and a practical tuning sequence.

Jul 11, 2026 · 8 min read

PLCopen Motion Blocks: MC_MoveAbsolute and Friends

PLCopen motion function blocks like MC_Power, MC_MoveAbsolute and MC_Home are the lingua franca of PLC-based servo control. Here is exactly how they work.

Jul 11, 2026 · 8 min read

HMI Tag Linking: Mapping PLC Addresses Correctly

HMI tag linking connects your screen objects to real PLC memory. Get the data type, polling rate or address wrong and your display lies to you. Here is how to do it right.

Jul 11, 2026 · 7 min read

SCADA Historian: How Process Data Gets Logged

A SCADA historian is not just a database. Learn how process historians compress, store and serve time-series plant data, and how to choose the right one.

Jul 10, 2026 · 8 min read

HMI Screen Design: Practical Rules That Work

Good HMI screen design is not about aesthetics. It's about operators making correct decisions fast. Here's what actually works on the plant floor.

Jul 10, 2026 · 9 min read

PROFINET IO: Controller, Device and AR Explained

PROFINET IO splits the network into Controllers, Devices and Supervisors. Learn how AR and CR objects work, cycle times, and how to configure them in TIA Portal.

Jul 10, 2026 · 9 min read

EtherNet/IP Scanner vs Adapter: How It Works

EtherNet/IP scanner and adapter roles explained: CIP connections, I/O vs explicit messaging, assembly objects, RPI, and step-by-step commissioning for Logix PLCs.

Jul 9, 2026 · 8 min read

PROFINET Wiring: Cables, Connectors and Topology

PROFINET wiring trips up even experienced engineers. This guide covers cable types, RJ45 vs M12 connectors, pinouts, bend radii, topology rules and common mistakes.

Jul 9, 2026 · 8 min read

Structured Text in TIA Portal: A Practical Guide

TIA Portal's SCL editor lets you write structured text on S7-1200 and S7-1500 PLCs. Here's the syntax, real examples, and when to use it instead of ladder.

Jul 9, 2026 · 7 min read