7.8 Automation of product packaging
Product packaging is one of the most frequent cases for automation in industry. It can be encountered with small machines (ex. packaging grain like food products) and large systems such as machines for packaging medications. Example we are showing here solves the classic packaging problem with few elements of automation. Small number of needed inputs and outputs provides for the use of CPM1A PLC controller which represents simple and economical solution.
By pushing START key you activate Flag1 which represents an assisting flag (Segment 1) that comes up as a condition in further program (resetting depends only on a STOP key). When started, motor of an conveyor for boxes is activated. The conveyor takes a box up to the limit switch, and a motor stops then (Segment 4). Condition for starting a conveyor with apples is actually a limit switch for a box. When a box is detected, a conveyor with apples starts moving (Segment 2). Presence of the box allows counter to count 10 apples through a sensor used for apples and to generate counter CNT010 flag which is a condition for new activation of a conveyor with boxes (Segment 3). When the conveyor with boxes has been activated, limit switch resets counter which is again ready to count 10 apples. Operations repeat until STOP key is pressed when condition for setting Flag1 is lost. Picture below gives a time diagram for a packaging line signal.
Ladder diagram: