Contactors and relays both switch circuits with a coil. How they differ in current, contacts, arc handling and use, plus how motor starters fit in.
What the two digits in an IP rating mean, the real difference between IP67, IP68 and IP69K, how NEMA ratings compare, and how to pick for washdown and outdoor use.
Incremental encoders count pulses; absolute encoders report a unique position. Outputs, resolution, single- vs multi-turn, and how to choose for your axis.
The four most common industrial Ethernet protocols compared: who backs them, speed and determinism, hardware needs, and how to choose.
How Modbus RTU and Modbus TCP differ, what they share, how to wire RS-485 correctly, and the register-addressing mistakes that waste the most time.
What Safe Torque Off means on a drive, how it differs from an E-stop or lockout, stop categories, and typical STO wiring.
How ultrasonic sensors measure distance with sound, what affects accuracy, and when to choose them over photoelectric or capacitive sensors.
Current loops and voltage signals compared: noise immunity, cable length, wire-break detection, wiring and how to scale the value in a PLC.
A plain-English guide to PLCs: what they do, the parts inside, the scan cycle, programming languages and the main types of PLC.
