SLC indirectly address a data table

Hi
I'd like to indirectly address a data file but
N[N7:255]:0 is thrown up an an error during verification.

What I wanted to do was store recipe data in consecutive data files.

Is there a way round?

thanks
pp

What's the error?

What does the rung look like?

Are you running through all of the possible N7 words? I'm not sure but if so, you might have a situation of N7 indirectly addressing itself ( N[N7:X] - where X = 7 ).

It should be possible.
SLC instruction reference says that you can indirectly adress the file portion of an variable.

What does the verify error code say ?
What value is there in N7:255 ?

It seems that the verifier loads the current value of the pointer, and checks that the indirect address exists. So you have to insert a value into N7:255, and the value must match a file number that allready exists ("7" for example for N7).

edit: Yes, the verifier accepts a pointer that points to itself.

HEY. This gives me a brilliant idea !

It would actually be possible to create a copy-protection, or tamper-protection for the program in the SLC !! (without having to lock out the complete program).

One place in the program, place a MOV instruction that indirectly adresses a file: Example MOV 1 N[N7:100]:0
The MOV instruction must not be executed. Place a JMP instruction before the MOV.
Somewhere else, place an instruction that puts a 0 in the indirect address: Example CLR N7:100

If somebody uploads the program into RSLogix it will not be able to verify. Only you will know that you have to put a valid address into N7:100.

Its not impossible to figure out, but it will deter the casual "meddler".

Thanks, Jesper.
The N7:255 still had 0 in - I'm still offline.

Like your idea, too!

pp