Louisiana Tech University
Lab 1
On my honor, I promise that I have not received inappropriate assistance on this assignment
Nicolas Long
Mr. Ron Gill
ICET 301 - Control Systems I
September 28, 2022
Inputs and Outputs
X0 is the input pin that represents the start push button. X1 is the input pin for the stop push
button. The start and stop push buttons are both momentary switches. The X10 and X11 inputs
represent the “valve on” and “valve off” sensors, respectively. The input valve can be opened
whether or not the pump is running. X12 is the input for the water level sensor. This sensor
detects the minimum amount of water in the tank in order for the pump to run.The Y0 output
represents the pump. The ST4 input is used to flash on and off in half second intervals.This
input is connected to the Y7 output, which indicates whether or not the pump is running. When it
is flashing the pump is running.
Logic
The start push button and pump are in a seal in circuit, which means that the pump is not able
to run until after the push button is pressed. Even after the push button is released, the current
is still going to the pump and it stays on. In order for the pump to start running, all conditions
shown in the ladder logic must be met. This includes the X0, X1, X10, X11, and X12 pins to be
true. The “valve on” and the fluid level sensors must be turned on in order for the pump to run.
The stop push button and “valve off” sensor must be off in order for the pump to run. These two
are hardwired as normally closed, so their natural state is “on”. The ladder logic showing them
as normally open means they are off. With all of these conditions satisfied, the pump will turn on
after pressing the start push button.This results in the Y7 output to flash, indicating that the
pump is running.
Ladder Logic
Conclusion
In conclusion, we did this lab to better understand how our PLC works and the ladder logic
behind it. This system was represented completely by the DoMore Simulation, but the logic is
the same as if it were connected to our actual PLC. In order to make the pump run, all
conditions shown in the ladder logic had to be met. This includes the valve off sensor and stop
push button to be off, the minimum fluid level and valve on sensors to be on, and the start push
button to be pressed. I was able to successfully control the valve and pump following the logic
shown in the lab instructions.