What is going on here

[SeanLee]

I have a program i am trying to edit and ran into something i dont understand

There are 2 integer files N7 and N11
In the program in the move comands and the math files they are addressed as
N11:[N7:4]
N11:[N7:5]
N11:[N7:6]
N11:[N7:7]
what is this method?

Thanks

 

[STL???]

Hi Sean,
Read through this thread:
http://www.plctalk.net/qanda/showthread.php?t=30791&highlight=AB+indirect+addressing

Look for Alaric's post.

 

[Mickey]

And heres what AB help has to say about "Indirect Addressing"

An indirect address is one that lets you substitute a word or bit number in a logical address with the value in another address. The processor uses the value from the substitute address to form the indirect address. You can use ladder logic to change the value stored at the substitute address.
Enter the substitute address in brackets [ ].

Example:
B3:[N7:1]/[N7:12] - In this example the word number is stored in integer address N7:1, and the bit number is stored in integer address N7:12.

 

[Ron Beaufort]

my distinguished colleagues Mickey, STL???, and Alaric should have you all straightened out ... but if you need just a little bit more help, here's a handy way to SEE what's actually going on ...

turn the checkbox ON and apply the change ... then turn the checkbox OFF and apply the change ... then experiment with different values in the "pointers" ... two or three minutes of this and you should have a firm grip on exactly how "indirect addressing" works ...

incidentally, you don't need a processor hooked up in order to try this out ... the RSLogix software will do this little trick all by itself ...