Star delta wiring

I have recently been given the problem of writing a programme for a PLC with 3 contactors KM1-star KM2-main KM3-delta with 2 push buttons PB1 stop PB2 start ,after pushing PB2 KM2 is energised and stays energised until PB1 is pressed the motor initially starts in star.
The programme must be dseigned in such a way that if KM1 is energised Km3 must be disabled and vice versa.
any suggestions greatly appreciated.

Dear mr. McFlynn.

This is an extremely basic problem to solve in a PLC program.
You should try to solve it youself. This because you do not learn anything from getting others to do your homework for you.
Even if you cannot solve it completely, a half-finished work that you have done yourself is MUCH better than a finished work you have just copied from others.

If you have some half-finished work, then we will gladly take a look at it.

Hi Jesper,
Thanks for your reply i figured out the problem it was just not explained very well in the question of where KM2 was to fit in.
Thanks Mark.

Dear sir what type of plc are you using , possibly i could be of help

Dear Sir,

I am using a Mitsubishi FXO series,its a fairly basic model.

Post your ladder logic / answer here to get some feedback then

mcflynn1977,
show us what u've got....
we'll show what we've got....

i cant determine your way to think, let us explore your ladder