The problem was chaos. Operators would skip steps, hit "EMERGENCY RESET" mid-dip, or manually open the drain while the coil was submerged. The old ladder logic was a 40-rung monster of interlocking seals that no one understood.
Transition from Step 20: Condition: (T#45s) AND NOT EStop_Pressed Supervisory Logic (Parallel Branch): IF EStop_Pressed THEN Jump to Step 99: EMERGENCY_RETRACT END_IF codesys sfc example
At 3:47 PM, a bearing seized on the acid bath agitator. The temperature spiked to 110°C. Acid_Temp > 95C triggered a pre-programmed fault. The problem was chaos
This is how industrial programmers think. Not just "code that runs"—but . hit "EMERGENCY RESET" mid-dip
