Beginner programming

Hello,

I am new to plc programming and I have been tasked with completing a work order that Im sure would be simple for a seasoned programmer and I need some assistance. I have two control valves for two different tanks. I need to reprogram these valves to have only one valve open at a time. In other words, when one valve is open the other has to be closed. Both valves are normally open contacts. Can anyone help with this?

your "work order" sounds like school assignment to me...

but anyway, some of the questions that arise...
- what PLC system do you use ? (hard/software)
- you need to reprogram, what does the original program do ?
- why/when should one valve or the other be open/closed?

grtz

button1 and NOT valve2 = valve1
the other one is slightly different