01 Opportunity
The packing end of the plant had grown machine by machine over decades: five standalone legacy PLCs, relay-heavy switchboards, hardwired safety and an ageing robot fleet that no longer matched the line speed upstream. Every carton the plant ships crosses this area.
That last fact set the rule for the whole project — the upgrade had to happen around production. No big-bang cutover, no commissioning window longer than a weekend, and the lines either side of each cell had to keep packing while it was rebuilt.
02 Solution
The PLC software was written from scratch on a standardised library: two fail-safe S7-1515F CPUs replacing all five legacy controllers, with modular per-cell logic so every cell reads the same way and any engineer can maintain any cell.
Six new palletising robots were integrated over PROFIsafe. The existing robots were kept and brought into the same architecture through a DeviceNet gateway — no forced fleet replacement, no stranded capital.
Safety was engineered per cell: PROFIsafe zones with gate access, light curtains and safe stops on ET200SP fail-safe I/O, so one cell can be entered while its neighbours keep running. PROFIsafe on the G120C drives and motor starters carried safety over the network instead of through the switchboard — removing around three-quarters of the components and wiring. New wrapping machines joined as PROFINET iDevices, IO-Link gave every sensor and valve terminal a diagnostic voice, and WinCC Unified dashboards report live throughput and shift KPIs for every line.
03 Outcome
The fleet was commissioned cell by cell around running production — the plant never lost a shift to the upgrade. Thirteen cells now run on two CPUs and one code library, with safety validated to SIL 3 / PL d and production running smoothly since commissioning.
Design, component selection, programming, safety engineering and commissioning were delivered by one engineer — one scope, one phone number, no interface gaps between contractors.
04 Project highlights
- 13 robot cells and automatic pallet lines commissioned cell by cell around live production
- Five legacy PLCs replaced by two fail-safe S7-1515F CPUs running one standardised code library
- Six new robots integrated over PROFIsafe; existing robots kept and integrated via DeviceNet gateway
- Safety engineered to SIL 3 / PL d — per-cell zones with gate access, light curtains and safe stops
- Around three-quarters of switchboard components and wiring removed with PROFINET-based drives and motor starters
- New wrapping machines integrated as PROFINET iDevices; smooth production since commissioning
