Conveyor & packaging control

The problem

Food, plastic, carton and light assembly shops in Bangladesh often run conveyors on a DOL starter and a handful of relays. The belt slams on, products pile up, and there is no interlock when a box is missing. Adding “a PLC” without an I/O list, sensor type and drive size creates a drawer of unused modules.

How this desk works it

We size the line as a loop: what the sensor must see, what the PLC must count or time, and what speed the motor actually needs. Proximity and photoelectric sensors handle presence and counting. A compact PLC (Delta, Siemens S7-1200, Mitsubishi FX, Omron CP1E) sequences start, stop, jam and reject. A VFD gives soft start so the belt does not jerk product. An HMI is optional until the sequence is stable.

What you walk away with

A parts kit that matches the machine — not a generic “automation bundle”. You get an I/O-minded quote: DI/DO count, sensor output type, motor kW and protection devices.

Working method

1. 01

   Map the sequence

   Infeed → sense → index/run → outfeed or reject. Write what happens if a box is missing.

2. 02

   Count I/O

   Each sensor, start/stop, overload trip and VFD run/fault is a point. We size the PLC from that list, not from a brochure.