An industrial robot performs a machine loading and unloading operation. A PLC is used as the robot cell controller. The cell operates as follows: (1) a human worker places a work part into a nest, (2) the robot reaches over and picks up the part and places it into an induction heating coil, (3) a time of 10 seconds is allowed for the heating operation, and (4) the robot reaches in and retrieves the part and places it on an outgoing conveyor. A limit switch X1 (normally open) will be used in the nest to indicate part presence in step (1). Output contact Y1 will be used to signal the robot to execute step (2) of the work cycle. This is an output contact for the PLC, but an input interlock for the robot controller. Timer T1 will be used to provide the 10 second delay in step (3). Output contact Y2 will be used to signal the robot to execute step (4).
(a) Construct the ladder logic diagram for the system.
(b) Write the low level language statements for the system.