function block common parametres in ControlLogix

[buhnen]

Hi all,

Here a pretty newbie question: I'm taking a look to some "interesting" instructions only available under the function block language in ControlLogix (at least not under ladder format), like PID or TOT. As I say, I'm only taking a look at it, haven't yet used the FB language in my projects, though even so,I`ve noticed there are always a set of common parametres like ProgProgReq,ProgOperReq,ProgStartReq,OperOperReq...and so on and I've got a bit of mess about this...could please someone give me a general approach or main idea about what these parameters are for in the FB language?

Thanks in advance to everybody.

 

[Ron Beaufort]

if your RSLogix5000 software was installed using the "default" procedures, then look under Help/Online Books/General Instructions ... the publication number on my system is

1756-RM003G-EN-P ...

go to page B-14 in the appendix for "Function Block Attributes" for a pretty good description of what these settings do ... see if that helps ...

 

[NOP]

You might also want to look at Rockwell Knowledgebase article 26407 which is more of a beginners/conceptual guide to modes of control.

 

[buhnen]

Thanks to both. I've found these texts very helpful.

 

[Ron Beaufort]

Greetings buhnen ...

I've recently posted some more information (here) which you might find helpful ...

 

[buhnen]

more on function block language

Hi again guys,

I don't know if this topic should be matter of starting a new thread with it but I think it's a pretty newbie question for. So there it goes anyway:

Under the ladder language I can easily perform the operation of adding a value constant (an integer number) to a variable (a DINT) and store the result in that same variable. This operation I've just described is basiclly a counter. But when trying to do the same under the block function language it seems like it's not possible because my variable (see the attached screen capture) is set automaticly to zero.
Any clue about how to solve this?
Thanks in advance.

 

[buhnen]

(In the picture above I forgot to mention that when I download the prog to the controller the "A" tag turn its current value from 20 to 0 automaticlly. This is what disconcerts me)

 

[Paulus]

(In the picture above I forgot to mention that when I download the prog to the controller the "A" tag turn its current value from 20 to 0 automaticlly. This is what disconcerts me)

Hello buhnen,
Not sure about AB (prepares himself for a good kicking from the Rockwell experts ), but many PLCs, (and this is really only for a general overview) when downloading a program are actually not running (i.e. they are in 'Program' mode.)
On restarting - switching to RUN mode - most memory areas are reset unless they have been specified as RETAINED, wherein these addresses / variables should keep their values.

I may be completely wrong, but just my 2c!

 

[curlyandshemp]

Hi again guys,

I don't know if this topic should be matter of starting a new thread with it but I think it's a pretty newbie question for. So there it goes anyway:

Under the ladder language I can easily perform the operation of adding a value constant (an integer number) to a variable (a DINT) and store the result in that same variable. This operation I've just described is basiclly a counter. But when trying to do the same under the block function language it seems like it's not possible because my variable (see the attached screen capture) is set automaticly to zero.
Any clue about how to solve this?
Thanks in advance.

In the ADD properties, did you enable the output?

 

[buhnen]

(yes, I had forgotten to tick the EnableOutput thanks for the tip!