1. Design and draw the schematic for a conventional hardwired relay circuit that will perform each of the following circuit functions when a normally
closed pushbutton is pressed:
- Switch a pilot light on
- De-energize a solenoid
- Start a motor running
- Sound a horn
A temperature control system consists of four thermostats controlling three heating units. The thermostat contacts are set to close at 50°, 60°, 70°, and 80°F, respectively. The PLC ladder logic program is to be designed so that at a temperature below 50°F, three heaters are to be ON. Between 50° to 60°F, two heaters are to be ON. For 60° to 70°F, one heater is to be ON. Above 80°F, there is a safety shutoff for all three heaters in case one stays on because of a malfunction. A master switch is to be used to turn the system ON and OFF. Prepare a typical PLC program for this control process.