Assignment:
Figure shows an automated hydroponics system. A PLC will be used to provide the following sequence of light and nutrient. The PLC has a 10-ms timer tick time, and the maximum count of timer and counters is 9999.
1. The growing vat must have light of minimum intensity for at least 8 hours. A photo-switch, which closes on rising light level, monitors natural light during this period. If the light intensity falls below the switch level for more than 10 minutes, an artificial light is turned on until the natural light brightens again.
2. During the 8-hour light period, nutrient must be cycled into the vat every 2 hours and left for 2 hours. Nutrient is filled to L1 (closes on rising level) and emptied to L2 (opens with dropping level).
3. During the remaining 16 hours, nutrient is pumped in, left for 3 hours, pumped out and left out for 1 hour, cycling for the 16 hours.
Provide complete and step by step solution for the question and show calculations and use formulas.