Use ext timer or code the timer ourself in PLC?

Hi,

I'm working on a program/system which require an timer to set the hour & day for the system to starts automatically.

It's on a Yokogawa FA-M3 PLC with a touch screen. Main purpose is better outlook of the system & save cost since there is a touch screen on it.

Does building a timer (same as ext timer function) in the PLC required a very complex ladder programming?

Anyone have a sample of it either in FA-M3 or RSLogix (AB)?

Thanks.

I'm not familiar with your PLC. If it has a real time clock, the programming should be very simple. You should be able to compare the day and hour with registers from the touchscreen, and when they are equal, turn on a bit to start the line. If the PLC does not have a real time clock, you will have to program one using a series of cascading timers. Here is how it would in a PLC5 with a real time clock. In this example, the Line Start bit will be on for one second.

If the PLC has a realtime clock, then you should definitely use it.

Only make sure that you display the time prominently on your HMI.
If/when the time drifts, then the operator must notice it and adjust it accordingly.

If the PLC do NOT have a realtime clock, then do not waste your time and try to program one yourself.
A relay with a realtime clock is not so expensive.

Jesper, just out of curiosity, could you give some info on these relays with RT clocks? That's something i haven't encountered before.

Thanks,
Paul C.

Okie,

The realtime clock is an actuall clock & calander built into the CPU just like on your PC. There's ususally a function in the programming software to set the clock/calander to your PC time & date. You might have an application such as a building alarm that will automaticly set/reset at spicific times of the day, days of the month, or even year. The realtime clock might also be used to timestamp events such as faults. You usually can refer to the realtime clock by seconds, minutes, hours, days, months & year individually, or the entire date & time value. The spicifics depend on the PLC brand and type.

One is Müller, but I cannot find their homepage (it is neither www.müller.com or www.muller.com !).

But you can find them and others at RS Components.
Browse to Automation ... Timers/Time Switches and Clocks ... Timers ... Digital DIN, voltage free.

Approximate price for such a thing is 60 Euro.

Okie,

Sorry about that...I miss read your question...lol..

(it is neither www.müller.com or www.muller.com !).

Click to expand...

nor is it www.mueller.com (which would be the way a German would have written it before Umlauts became available in interner addresses), the address exists, but it's a sheet metal shop, or something similar!

I've used these on a very limited basis. These have everything you need and many things that you don't.

http://www.brgprecision.com

I'ved used the 4 digit with syn functions and 10Amp relay output. I would be careful about auto starting lines that could possible have someone in the way though. My system uses a start button that sounds an alarm for 5 seconds to allow everyone to be notified that a start is going to occur. I am thinking of changing it to require a second push after the 5 sec. to start. That way if you hear anyone yell, it won't start automatically and hurt someone. Just my 3 cents, since I don't know what you are auto starting. I would approach it cautiously though,

Web address suggestion

I have not heard of Muller personally. Is the company located in Germany? If so, maybe the company web address is www.muller.de (or the like).

Rick

I found it:
http://www.hugo-mueller.de/englisch/Startpage-english.htm

It was mueller (like RMA said) and .de (like rgurin said).
Then add "hugo" and viola !