PID Control in Omron (Level Control)

Hi there,

I am a programmer (beginner) in programming Omron PLC's and require some assistance in designing a PID control loop to control the level of a tank system. The level is to be control by PID automatically and this is how the system is connected.

Pump through flow transmitter via flow valve (ATC) to tank
Tank to level transmitter through level valve (ATO) to drain

I need some basic help on how to incoporate the readings obtained from the transmitters, the PLC logic and the signal sent to the valves to maintain the level to a setpoint.

Thanks in advance