Question: Devise ladder programs for systems that will carry out the following tasks:
(a) Switch on a pump when the water level in a tank rises to above 1.2 m and switch it off when it falls below 1.0 m.
(b) Switch on a pump; then 100 s later, switch on a heater; then a further 30 s later, switch on the circulating motor.
(c) Switch on a heater when the temperature is less than the set temperature.
(d) Turn on a lamp when a data source is not giving 100.