10252 Liquid Filling Machine

Project Type: Food Processing Spring 2010

Summary & Goals

Customer had a machine that filled two buckets on a conveyor system with a liquid product. The controls on this unit were custom designed by an integrator that did not want to release the program to the customer even though the customer owned the design. Logicon was asked to reverse engineer the system and apply a new design using Allen-Bradley controls that the plant was able to support on their own.


The machine was a dual-head filler and was controlled with “C” programming language written in a proprietary weigh scale unit. The customer was forced to call upon the developer for any changes or repairs no matter the situation. This caused much downtime and frustration for the customer on several occasions. Logicon was asked to replace the system with one that could be easily maintained by the plant and their internal abilities.


To match other platforms in the plant, Logicon selected the CompactLogix PLC from Allen-Bradley. This platform conveniently offered a Hardy weigh scale module that fit in the chassis which aided in the design as the physical size of the control needed to fit in the existing control panel. The card provided wiring ability for up to 2 weigh scales and was fully integrated into the ladder logic for tare, zero, and calibration.

Logicon completed the HMI and PLC design in house then performed a field installation of the new backplate into the existing enclosure. After a couple days of testing and trial runs, Logicon completed operator training and remained on site for the week to verify all sequences, make requested changes and answer any additional questions during the week’s production.

The machine has been running successfully since startup and Logicon has been notified of the customer’s intent on performing the same upgrade project on another dual-head filler machine in the same plant in the near future.


Logicon produced a replacement backplate for the control panel. The new touchscreen included sequential operation screens for a few of the operator performed tasks that previously were completed manually thus eliminating operator error for that process. Due to the advanced operator controls and the simplification of calibration of the machine, the machine now runs with only a single operator, down from a previous 3-4.

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