Fixed versus Modular PLCs 2

[oddmanout]

I am currently taking a course in PLCs. Would someone please define the terms "fixed" and "modular" PLCs? What are the major differences between the two?

Thank you.

 

[ScottyUK]

Jeez, does it? I had never realised! Thanks for clearing that up.

I can't think of any PLC where you directly interact with the A/D and D/A hardware, in fact the only way in is usually through the system register which allows you restricted access to certain parameters. All the ones I've worked on use a text or graphical interface to represent ladders and loops and screen the user from the hardware. Obviously you know better!


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Sometimes I wake up Grumpy.
Other times I just let her sleep!

 

[Skogsgurra]

Probably. There are such animals. Just google "analog memory".

But I doubt if that is what was meant.

(Now, I expect quite a few posts telling me how wrong I am and that I don't understand the subject)

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[dV8r]

I'm surprized that there are people using PLC's and do not understand how they work. All digital electronics are made up of two state devices either "ON" or "OFF". It is very simple, the complexities come in when one starts to string these together and cascade them by the millions. Or is it done differently in the UK?
And no, the analog memory device has not been perfected yet.

 

[ScottyUK]

Interesting that you think we have forgotten how the digital computer works. After all it was invented in the UK. Let me see... one, zero, yes I think I can follow that.

Any application programmer who uses the PLC does not normally write the application program as a series of 1's and 0's direct to the processor memory, nor in assembler code, nor even a mid- or high-level programming language such as C or Pascal. He uses the software from the PLC manufacturer or a third party vendor which presents him a graphical or text based interface which does the job of interacting with the digital world of the microprocessor. Have you ever programmed a PLC? It is difficult to tell from your posts.


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Sometimes I wake up Grumpy.
Other times I just let her sleep!

 

[Madcow]

Is a capacitor not an analog memory?

 

[pooslinger]

Oddmanout:
I like the way you defended yourself. Did you notice that the sarcasm went away and people started answering your question? Good reading for a not so informative question. Either you textbook is out of date or you instructor has been out of the “real world” to long if he or she ever was. A confidant good defense is a trait that is not seen much anymore. Those who have it go far. (Oh my God, I sound old)

 

[skills]

Yes, Oddmanout, you showed great patience and restraint in your response. Good show.

 

[jaraff6675]

I'll bet I have a N.I.B. AB SLC-100 behind a ton of boxes, maybe I'll stick it in a museum.

 

[oddmanout]

I would like to sincerely thank all of you for your very informative responses. A lot of good reading here re: background information on PLCs that I was totally unaware of and is not mentioned at all in my course materials.