PLC (pick and place ) keyence

Hi, I'm doing a program but i seem to have some problem.
hope that someone out here would be able to help me out.

First of all here's the scenario. there 3 cylinder.. name A, B and C
there's a start and stop bottom, a sensor and a vacuum.

when start button is press, Cylinder A which has a vacuum and a sensor attach to it. It will fully extended to pick the seed up. if the sensor did not sense any object that is been pick, it will repeat the Cylinder A extend and retract process again till the object is been pick then it will carry on by moving Cylinder B and C together to a point where it stop and fully extend Cylinder C to drop the seed and retract back. then Cylinder B and C retracts back to the original position
remarks this process is continues.

C+ | C- | A+/B+ | C+ | C- | A-/B-

A is using 3/2 way valve with single solenoid spring return

both B and C is using 5/3 way valve with double solenoid.

there's 2 reed switch for every cylinder.

You may need to specify your problem in order to receive some relevant insight.

for the Cylinder A i have a problem doing a repeat cycle for the sensing of the seed if its not been pick.