Exercise #1 -- Filling the Batch Mixing Tank
From the Simulations Menu at the top of the screen, Select the Batch
Using your knowledge of PLC counters, design a program to
meet the following requirements:
- When the Start switch (I:1/0) is pressed, pump P1 will be energized
and the tank will start to fill. The pulses generated by Flowmeter 1
should be used to increment a counter.
- When the count reaches a value where the tank is approximately
90% full, the pump is to be shut-off and and the control panels FULL
light is to be energized.
- The filling operation is to halt immediately if the stop
switch is pressed.
- While testing, utilize the "Reset Simulation" and the "Reset Timers
and Counters" entries in the Simulations menu to re-start your
To make it a little easier to see what is happening with the counter,
you might want to add the following rung to the end of your program.
If correctly entered, the TOD (To BCD) instruction will take the integer
value in the counters accumulator, convert it to Binary Coded Decimal, and
then move (copy) this BCD value to the control panel LED display (O:4).
The TOD instruction can be located in the Compute/Math group of instructions
in the Edit Panel. Be sure to alter the Source entry to match the counter
number you are using.
Exercise #2 -- Emptying the Batch Mix Tank
Exercise #3 -- Continuous Operation
Modify your program so that the filling and emptying sequence
will repeat continuously once it has been started by the initial
pressing of the Start switch.
Ensure that the RUN light is energized when the mixer or either
pump is running.
The STANDBY light should light and the process should halt when
the Stop button is pressed.
The process should restart where it left off if the the Start
button is pressed following a Stop.