Programming instructions

65
10.4 EXERCISE Ladder Basics
1) X1 turns on and sets Y3. What happens to Y3 when X1 turns off?
2) What type of symbol would you use to represent a standard E-Stop in
ladder logic? (Yes, E-stops are commonly hard-wired, but are often
referred to in other parts of a program for various reasons)
3) List the common basic symbols (like ) and describe what
they do.
4) List the common basic instructions (like PLS) and describe what they
do.
5) What is required for a rung to be a complete circuit?
6) On the main conveyor, a sensor (input X2) checks for the presence of
a certain package. When one is detected, the sensor switches on and
turns on a pusher (output Y7). The pusher stays on until the package is
detected by the side conveyor sensor (X3). When Y7 turns off, the pusher
automatically retracts. Write the logic to accomplish this.
NOTE: As the package is pushed, it leaves the detection area of the main
sensor before being detected by the side conveyor sensor.