Industrial PLC — Where Software Meets Steel

Before web APIs, there were wires. Industrial automation taught me that software has consequences you can hear — a bad line of logic does not throw an exception, it stops a production line or pinches a finger. I program PLCs in Ladder Diagram and Structured Text under IEC 61131-3, and I design the HMIs operators actually use.

What I do on the floor

Area	Practice
Logic	Ladder (LD) for discrete control; Structured Text (ST) for math and sequences.
HMI	Screens operators can read at a glance, in their language, with honest alarms.
SCADA thinking	Tag naming, alarm rationalization, data logging that survives audits.
Safety	Interlocks first, convenience second — always.

Automation made me a better software engineer in three specific ways: I respect state machines (a line is one giant state machine), I write defensive code (sensors lie, contacts weld), and I document as if the next reader is standing next to a running machine — because sometimes they are.

In industrial control, uptime is measured in tons, not nines.