Panel Design

Step 1's I/O list defined every point each station's PLC needs to read or control. This step turns that list into an actual control panel — I/O card count, enclosure sizing, and power distribution — for each of the 3 stations.

Each station gets its own control panel, sized to its specific I/O count from Step 1: the digital input/output count and analog input/output count both drive the PLC's I/O card selection (a modular PLC rack takes discrete digital I/O cards and separate analog I/O cards, each with a fixed point count — 8, 16, or 32 points per card depending on the family), and the total card count plus the PLC's own CPU/power supply module determines how many rack slots — and therefore how large a rack — each station actually needs.

Enclosure sizing isn't just fitting the PLC rack — it has to account for terminal blocks (one per field wire landing, which adds up fast on a station with dozens of I/O points), power supplies (24VDC for the PLC and most field devices, likely a separate supply for any servo or VFD control circuits), and thermal dissipation from everything running inside a sealed enclosure, which is a real design constraint once you're sizing for a food/beverage plant floor environment (washdown-rated NEMA 4X enclosures are common in this industry, and they trap heat more than a ventilated NEMA 12 enclosure would).

Power distribution within each panel — from incoming line power down to 24VDC control power, VFD/servo drive power, and field device power — has to be laid out with proper isolation between power and signal wiring (a classic industrial-controls mistake is routing analog signal cable in the same wireway as VFD output power, which induces enough electrical noise to corrupt the analog reading). Getting the panel layout right here is what makes Step 3's network architecture and Step 6's FAT/SAT testing straightforward instead of a troubleshooting exercise.