What do I need to make program to control valve

I am new to the group and to PLC's. I have gotten my hands on a GE fanuc 90-20 micro, and want to use it to program a 24V irrigation vavle to be open for 10 minutes, and then close for 10 minutes, I want this cycle to repeat continuoulsy around the clock. I Have the valve, SSR, 24v power source, and the PLC. My question is does the PLC have an internal clock to trigger the valve? or is some kind of external device needed?

Thanks,
Doug

Welcome to the world of PLCs and this forum. Read the manual that came with your GE unit or download one from the GE controls web site. To answer your question, the PLC you have will do all you need, once you write some code(a program) to make it happen. A clock, per se, is not required.

The 90-20 does not have an internal clock/calendar. It does have timers and counters in its function set. If you're not too concerned about synchronizing your valves to the time of day, it will work just fine.

Simply create two timers with ten minute presets. When the first timer reaches its preset, turn on the valve and start the second timer. When the second timer reaches its preset, reset both timers.

Incidentally, the 90-20 has been obsolete for years.

Thanks for the replys. I figured it was obsolete, as I can't seem to find a manual on the GE site. The unit was given to me, but I fugure it should work fine for what I want to do with it?

What If I want to control 6 valves and have 3 on for 10 miuntes, while the other 3 are off, and then switch the 3 on to off, and the 3 off to on?

Thanks for your help,
Doug

The publication number for the 90-20 manual is GFK-0551C.

Do you have programming software for the 90-20?

The method I outlined will work for what you want to do. While both timers accumulated values are less than their preset, turn on one bank of valves, when the first is greater than preset but the second is less than preset, turn on the second bank of valves.

If necessary, you could set up individual timers for each valve. Each timer requires three data registers. The 90-20 has 256 data registers, so you could create as many as 85 timers.

Steve, thanks for the help on the manual, I did find it. I do not have the software, what do you reccomend?

Doug

For a 90-20, it appears that your only choice is Logicmaster. That's the old DOS-based software that dates back to when the product was first introduced in 1990.

There have been a couple of evolutionary steps since then. The first was called VersaPro. I don't see the 90-20 listed as an option when I create a new project with it.

The current offering is called Proficy Machine Edition, but I don't see the 90-20 listed as a CPU option there either.

Logicmaster is included on the VersaPro installation CD.