ON/OFF output using PB in Auto/Manual mode

[darrenj]

. PB B3:1/14 is actually named PV_MODE_PB, the YELLOW background part is descriptions which in this case show what is happening...ie if 0 then its Manual, if its 1 then its AUTO.

mmmm..Not going to diasgree here becouse i am not sure..But i dont think you are right on this one Ron..As far as i have seen in rslogix if i label B3:1.14 something it stays that way through out the program..I dont beleive it can change depending on the state..

AGAIN..i say i dont think..i am not sure..

 

[rsdoran]

I left out one thing though. B3:1/14 (or any other instruction) will retain the same name regardless of state (0 or 1). The Panelview though can use ONE address like B3:1/14 to show different states...ie Manual if 0 and Auto is if 1.

 

[tom_stalcup]

RSLogix will let you choose either the INSTRUCTION option or the ADDRESS option when entering the ladder code. If you use the INSTRUCTION option, you can then have(as terry pointed out) one description for an xic bit, and another for the xio bit. I don't recommend doing this for regular instructions..... It makes the program a little hard to follow sometimes.
However, using timers, counters, etc. is a different animal. I really like being able to say that the "timer timing" bit does one thing, and the "timer done" bit does something else.

 

[rsdoran]

darren, I wasnt saying it could be different, I was stating what was being done with the symbol name (in green) and the descriptor (in yellow). The descriptor is showing that when B3:1/14 is 0 its in manual and when 1 its in Auto. I do not know of a way to describe or name an XIO or XIC with the same address different.

RSLogix will let you choose either the INSTRUCTION option or the ADDRESS option when entering the ladder code. If you use the INSTRUCTION option, you can then have(as terry pointed out) one description for an xic bit, and another for the xio bit.

I have RSL500 ver 5.2, I cannot enter a different description or name for an adresses xio and xic bit. The data table only offers a place for one name and description per address. In the above pictures the address is shown, the symbol name (in green) and the description (in yellow).

Can you explain how to do it? I am not sure what you mean by INSTRUCTION or ADDRESS option.

 

[chavak]

Ron,

Please see the image, when you key in the description for the instruction there are 2 options.

The "instruction" option gives you to configure separate descriptions for different states.

 

[Unregistered]

Dumb Question

I'm new to PLC's and have bought a copy of rslogix 500 and have a 500 brick to play with,

What I don't understand is why all your examples are written using bits only?

I have had no formal instruction but understand bits to be internal (inputs and outputs) for the sake on not having to loop wires around and use up all you real inputs and outputs.

Why are all the examples only in bits

Clint

 

[Terry Woods]

"What I don't understand is why all your examples are written using bits only?"

I understand that you don't understand. However, your question is too broad in it's scope. That is, the question begs an answer that ranges from why bits are used at all... to... why bits are used instead of ...?

What did you expect to see?

 

[darrenj]

Ron,

Please see the image, when you key in the description for the instruction there are 2 options.

The "instruction" option gives you to configure separate descriptions for different states.

well now you DO learn something new each day!..Apologies Ron i had no idea this could be done.

 

[rsdoran]

ME either

Couldnt this get confusing? I did not want to know this was possible.

In this case bits are being used because the original poster was working with a Panelview (HMI) for his pushbuttons. The pushbuttons may turn on other bits instead of directly activating an output for numerous reasons.

 

[DanielCamacho]

To all....

This is a more acceptable way to decribe you dual usage bits:

 

[Terry Woods]

All bits are inherently dual-usage...

If the particular signal is ON then the named condition is TRUE.

If the particular signal is OFF then the named condition is FALSE.

Condition Names really count!

I think it really boils down to properly naming the conditions... as I have always stressed!

As much as I really love the idea of separate Names for the positive and negative states of a particular bit, I'm am examining and attempting to reconcile the issues (possible confusions) involved.

There is the posssibilty that the process is in neither AUTO nor MANUAL.

There are. clearly, possible conflicts in interpretation.

 

[Eric Nelson]

You're gonna have to explain this one...

There is the posssibilty that the process is in neither AUTO nor MANUAL.

C'mon, Terry. If 1 = AUTO and 0 = MANUAL, then what value is "neither AUTO nor MANUAL"? 0.5? 2?...



-Eric

 

[Terry Woods]

It all depends on how Auto/Manual is invoked.

If there is simply a switch that says Auto or Manual, then fine... the process is either in Auto or Manual.

If, on the other hand, it requires an explicit transition-type declaration (PB or otherwise) to actually go to one mode or the other, then, upon start-up, and until the declaration occurs, the process is in neither Auto nor Manual.

It can happen... it's simply a matter of programming. Who knows what some programmers will do.

Just tryin' to cover all possibilities.

 

[Eric Nelson]

If there is simply a switch that says Auto or Manual, then fine... the process is either in Auto or Manual.

I didn't realize you were talking about other applications. In this application, there IS simply a switch, er, maintained PB. That's what I thought you were referring to.

Nice to know you haven't lost your mind (at least not yet)...



-Eric

 

[rsdoran]

Terry thats why I didnt like the way all this went from the beginning. The application seemed to want an option to hit start and run or manually "JOG"...its all in the descriptions. I doubt I would ever use 2 names/descriptions for one address.

We all know I am simple and not really good at this. My strong points are I will not stop trying and once in a while stumble onto something.

Above I noticed many tries that used multiple rungs that got shot down for one reason or another. Maybe they would or would not work the problem is there were so many rungs for something I thought should be in 1 or 2 rungs like I did above. I have redone it using AB so tell me what you think...I have more 1 rung concepts.