Latched relay?

Norman · Jul 7, 2004

I want to turn on and off an output with one button,my minds blanked at the moment
I want to press the button to turn on and then pres the same button again to turn off.

Anyone help please.
Norman

randylud · Jul 7, 2004

Norman,
What you need is a Flip-Flop and you can search this forum for that subject and find many threads on the subject. Good luck!

Norman · Jul 7, 2004

Thankyou I have this sorted now,brain was not good earlier
Norman

Don_Dubé · Jul 7, 2004

I have seen several ways of doing this depending which PLC platform you are using but I think that the easiest way to do this is by using a simple Count up counter. Have the count increment by one each time you press the P.B. and then compare the current value of the counter, when the value is equal to 1 turn on a coil. You will need to reset the counter and you will also need a one shot to avoid the counter incrementing every PLC scan.

Feel free to e-mail me and I can forward you an example

Best regards,

Don

Friedrich Haase · Jul 7, 2004

Norman said:
I want to turn on and off an output with one button,...

Here a sample in IEC 61131 ladder diagram. Hope it helps.

Friedrich

sonarbell · Jul 7, 2004

Try this if you are using RS Logix 5 or 500

lightninguk · Jul 7, 2004

If its Mitsubishi code, try this.

X0-------------------------[ ALTP M0 ]
M0--------------------------( Y0 )
---------------------------[ END ]

Regards Lightning

93lt1 · Jul 7, 2004

I came across this once. It actually works (at least in Controllogix), and is used several different places in the program.

Notice that 2 of the one-shots have the same address.

93lt1 · Jul 7, 2004

sonarbell said:
Try this if you are using RS Logix 5 or 500

Here is a screen shot of sonorbell's file.

I am not sure what is the purpose of B10:19/8 and B50:0/2 maybe a typo?

panic mode · Jul 7, 2004

Nahh.... There are number of ways to do it but I've decided
to stay with one shot and XOR block. It's simple one line logic
and toggled bit stays on powerup so it can be used for
machine configuration.
I've found the hard way that XOR logic with contacts as posted
by Friedrich can bite back...
Just toggle darn bit(s) as selected with mask and forget it.

93lt1 · Jul 7, 2004

I agree, I have my own preferred way to do it and I'll stick with it. I think I've seen at least 10 different ways to do it, and each takes a few minutes to figure out what the heck is going on.

I guess there's something that won't let me address 2 one shot's with the same address and keep a clear conscience.

sonarbell · Jul 8, 2004

Oooppppsss Sorry Chaps. Typo's galore. Try this one instead.

Allan Barnes · Jul 8, 2004

How about Low Tech?

How about a real Low Teck Solution

"I want to turn on and off an output with one button,my minds blanked at the moment
I want to press the button to turn on and then pres the same button again to turn off."

Use a Maintained Switch

cnrservices · Jul 8, 2004

Allan,

Use a Maintained Switch

That probably would work for someone other than a PLC programmer.

A person could just as easily buy an Omron temperature controller & have it turn a contactor on & off - but where's the fun in that? The same result can be achieved with analog inputs, 12 hours & 45 lines of propriatary code.

This is PLCs.net after all

93lt1 · Jul 8, 2004

cnrservices said:
but where's the fun in that? The same result can be achieved with analog inputs, 12 hours & 45 lines of propriatary code.

Strange how that works, but it is the truth, isn't it...

Latched relay?

Norman

Member

randylud

Member

Norman

Member

Don_Dubé

Guest

Friedrich Haase

Member

sonarbell

Member

lightninguk

Member

93lt1

Member

93lt1

Member

panic mode

Member

93lt1

Member

sonarbell

Member

Allan Barnes

Member

cnrservices

Member

93lt1

Member

Similar Topics