LogixPro
The Advanced
Batch Mixing Lab

A Programmable Batch Mixing System

Exercise #1 -- Single Batch Mode of Operation
Using your knowledge of PLCs, design a program to meet the following criteria:

• When the 3 position Selector Switch is in position "A". the batch mixing process will run in a single batch mode. The operator may start the batch mix sequence by momentarily pressing the Start Switch.

• Once a batch sequence has begun, the sequence may be stopped and resumed at any time using the Stop and Start switches.

• The tank is to be filled with a mixture obtained from the separate fill lines utilizing fill pumps P1 and P2. A counter will track the quantity of product obtained from Line 1 (P1) while the remainder will come from Line 2 (P2). The mixture ratio of the product will be controllable by adjusting the counter's preset. The tank is to be filled to the point where the Hi-Level sensor goes true.

• When filling is complete, the Full light will turn On. Heater O:2/04 and Mixer O:2/00 will be started allowing the mixture to begin heating. Thermostat I:1/02 will be employed to control the temperature.

• The mixer will continue to run for 4 seconds after the mixture reaches the desired temperature. When the mixer stops, pump P3 will be used to drain the product from the tank. The tank will be drained to the point where the Lo-Level sensor trips.

• Once emptied, a new single batch sequence may again be started by pressing the Start Switch while the Selector switch is in position "A".

Exercise #2 -- Multiple Batch Mode of Operation
Enhance your program to include the following features:

• When the 3 position Selector Switch is in position "B". the process will produce multiple batches, The number of batches produced will be operator selectable, and the current batch count will be displayed on the Control panel's LED display.

• The operator will be able to enter the desired batch count using the control panel thumbwheel switches.

• The operator will be able to set the product ratio by entering the desired product one percentage via the control panel thumbwheel switches.

It is your responsibility to make the operator interface as simple and fault tolerant as possible.