please show all steps and explain if possible. thank you very much
Q3. A PLC is used to control an automatic door into a warchouse. Four input devices are used to develop control signals to the PLC: - An ultrasonic device which switches ON as the vehicle approaches the door. - A photoelectric switch which de-activates (goes OFF) as the vehicle is passing through the doorway. - At the top and bottom positions of the door travel there are limit switches that indicate the position of the door. When the door is in the down position and the ultrasonic device senses the approach of a vehicle, the PLC will signal the motor drive mechanism in forward direction to open the door until it reaches the upper limit. Provided that no vehicle approaching and no obstruction of the door way, the upper limit switch signal, will signal the motor drive mechanism in reverse direetion so closing the door until the bottom limit is reached. In developing the control program note the following points: i) That vehicle clears the field of view of the ultrasonic sensor before passing through the door. ii) That the vehicle may well elear the photoelectrie sensor before the door reaches upper limit. iii) If a vehicle approaches door while it is coming down it should immediately start going up. OUTPUTS: UP Motor for ME47I4-Instrumentation \& Control, 2022 pages 5 Q3. A PLC is used to control an automatic door into a warchouse. Four input devices are used to develop control signals to the PLC: - An ultrasonic device which switches ON as the vehicle approaches the door. - A photoelectric switch which de-activates (goes OFF) as the vehicle is passing through the doorway. - At the top and bottom positions of the door travel there are limit switches that indicate the position of the door. When the door is in the down position and the ultrasonic device senses the approach of a vehicle, the PLC will signal the motor drive mechanism in forward direction to open the door until it reaches the upper limit. Provided that no vehicle approaching and no obstruction of the door way, the upper limit switch signal, will signal the motor drive mechanism in reverse direetion so closing the door until the bottom limit is reached. In developing the control program note the following points: i) That vehicle clears the field of view of the ultrasonic sensor before passing through the door. ii) That the vehicle may well elear the photoelectrie sensor before the door reaches upper limit. iii) If a vehicle approaches door while it is coming down it should immediately start going up. OUTPUTS: UP Motor for ME47I4-Instrumentation \& Control, 2022 pages 5
