Differences Between PLC Output Cards

charliep · Jan 21, 2004

What is the difference between discrete, analog and relay output cards?

Mark Buskell · Jan 21, 2004

Discrete

The spelling

panic mode · Jan 21, 2004

Discrete outputs are only ON/OFF and this is further
clasified by the type of output (relay, transistor, triac).
Analog outputs are providing signal that can gradualy
change from one value to another. Standard ranges are
for example 0-10V, -10 to +10V, 4-20mA, 0-20mA.

Mylo · Jan 21, 2004

Panic Mode to the rescue !!!

Your just too Damn nice, ye know that.........

Can you help me with my Traffic Light Machine??? honest its for work...........

Mark Buskell · Jan 21, 2004

Discrete

You are right about the traffic lights.

It must be January and classes have begun AGAIN. What amazes me is some of the questions that we get and with just a hint of initiative, the student could found out the answer easily enough. I did a google search on "Differences between discrete and analog" and found the answer in less than a minute. Maybe they need to teach Google 101.

P.S.
What is a normally open switch?

charliep · Jan 21, 2004

There seams to be a bit of confusion with the way the question is worded. I'm looking for the physical difference between the types of output cards. Sorry for not being an engineer.

hd_coop · Jan 21, 2004

you don't need to be an engineer to word a question properly.

physical differences: they circuits are different (obviously), the terminal blocks may be different

since all cards for a given PLC must go into the same slot, there is little variation for physical difference between cards.

why do you need to know this?

Steve Bailey · Jan 21, 2004

Generally, within a given PLC model, most I/O modules can be mounted in any available location. Given that, the physical differences between them reduce to the components the manufacturer uses to accomplish the module's function.

Tom Jenkins · Jan 21, 2004

The biggest physical difference is the volume of contained smoke and the threshhold voltage for releasing the smoke. For example, with an analog card 120 VAC is usually sufficient to release all of the smoke. With discrete relay outputs, it may require more than 600 volts to release the smoke.

panic mode · Jan 21, 2004

I guess flu got me and I wasn't thinking straight...
I will do my best to confuse next candidate.

Differences Between PLC Output Cards

charliep

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Mark Buskell

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panic mode

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Mylo

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Mark Buskell

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charliep

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hd_coop

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Steve Bailey

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Tom Jenkins

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panic mode

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