Bulk-Bag Filling Line — PLC and HMI from Infeed to Outfeed

Problem

A vegetable-oil plant was installing a big-bag filling line, supplied with weighing equipment from a specialist vendor. Material is fed from a hopper, filled into a bulk bag hanging on a weighing frame, and the full bag leaves on a pallet conveyor, with a dust collector on the filling head. Every machine on the line needed one control program and one operator screen, commissioned inside a plant that kept producing.

My role & scope

I wrote the PLC program and the HMI myself, for the whole line — from the infeed at the start to the pallet conveyor at the end — and commissioned them on site with the weighing-equipment supplier and the plant’s operators, including night shifts so testing did not stop production.

Approach

One program for the whole line

The line runs as one sequence: feed, fill, weigh, release the bag, move it out. The program covers every machine on it — feeder, dust collector, filling head, conveyor — and the sequence that runs them in order, so the plant has one place to look when the line stops.

Fill by weight

The operator enters a set weight for the bag. The screen shows setpoint and actual weight side by side while the bag fills, and the sequence stops the feed when the target is reached.

One screen for the whole line

The HMI shows a process overview of the full line with each motor and valve in its running or stopped state, so the operator sees where a bag is and why it is waiting.

Delivery

• I/O check of every device against the drawings
• Each machine tested on its own, then the full sequence — first empty, then with product
• Commissioning on site with the supplier and the plant’s operators
• Handover of the PLC and HMI program backups

Result

• The line runs from infeed to outfeed on one program and one operator screen that I wrote
• Bags filled to a set weight, with setpoint and actual weight visible to the operator
• Commissioned without stopping the rest of the plant

Skills used

Siemens S7-1200 and TIA Portal V17 · Siemens HMI screen design · machine sequences and interlocks · weighing and batching · material handling and dust collection · commissioning in a live food plant.