Having trouble understanding this ladder logic program. I can solve more basic ladder logic programs but I do not know how to account for small voltage adjustments. Here is the problem:
You are designing a PLC program which controls a cooling van on a vehicle engine. The engine must stay at 205 degrees F. The PLC should have 2 outputs for fan control: an output which turns the fan on and off, and a second output which is a voltage value which corresponds to the speed of the fan. The fan speed voltage should be between 0 and 5 volts, where 0 V indicates a slow fan for 1 degree above temperature (206 degrees) and 5 V indicates maximum fan speed for 10 degrees above temperature (215 degrees). The input to the PLC is a thermopile which is 0 V at 150 degrees F, and increases by 25 mV for every degree F above that. The system should also have a third output which is an overheat light which flashes if the engine temperature ever reaches 15 degrees above the temperature setpoint (220F).