A small packaging machine looks simple: a film roll, a heater bar, a cutter, a counter. Then you open the cabinet and find forty relays, three timers and a rat's nest of wire that nobody dares touch. Sound familiar? This is the classic machine that xLogic replaces in an afternoon.
Take a typical vertical form-fill-seal line. It needs counting, sealing temperature control, and a handful of interlocks. On relays that is a week of wiring. On an xLogic nano PLC it is about forty function blocks.
The Machine and the Pain Points
- Counting hundreds of bags per minute — a relay counter cannot keep up, and miscounts mean short packs that fail QC
- Sealing temperature that drifts — too hot burns the film, too cold leaks the seal
- Logic changes that require rewiring the whole panel
- Cabinet space and budget that are both tight on a low-cost machine
The Solution: One SR-12DC-DA-R
The SR-12DC-DA-R handles all four jobs on one 12-point CPU. A photoelectric sensor on the film path feeds input I5, which is a dedicated high-speed counting channel — 65 kHz on this model, far beyond the speed of any bag counter. The counter output triggers the cutter and advances the seal cycle.
Sealing temperture runs through the built-in PID loop. A thermocouple or PT100 signal comes in on the analog input, the PID block holds the heater bar at setpoint, and the relay output drives the SSR. Drift that used to cost a production supervisor his lunch hour is now a non-event: the LCD shows the live temperature, and the operator adjusts the setpoint from the keypad without opening the cabinet.
The whole program — counter, PID, timers, interlocks — downloads from xLogicSoft in under a minute, and the simulator catches logic mistakes before the machine ever sees power.
What the Customer Gains
- Cabinet shrinks: one DIN-rail module replaces the relay stack — smaller panel, less wiring, lower cost
- Miscounts stop: 65 kHz counting beats any mechanical or relay counter on the market
- Seal quality stabilizes: PID keeps the bar within a degree, so film waste drops
- Logic changes are free: alter the count target or add an alarm from the PC — no rewiring, no downtime beyond the download
Did we mention the price? A relay panel with this much logic costs more than the PLC, and still cannot count at 65 kHz. The math was not close.
Recommended Models for Packaging Machines
| Model | Best for |
| SR-12DC-DA-R | Counting + temperature PID on a compact 12-point CPU |
| SR-22DC-DA-R | More I/O, more flags (256 AF + 256 F) for bigger wrappers |
| PR-12DC-DA-R-N | When you want the LCD, keypad and 1024-block memory for recipes |
Related: high-speed counting explained · Selection Guide · first FBD program tutorial
