DDV Instruction

[shoelesscraig]

Ok, so I consider myself reasonably intelligent, but I need help with this one. I would like to better understand the Double Divide instruction in AB logic. I have read the instruction set manual, but it isn't quite clear. Does someone mind putting this is layman's terms? Maybe an example of when you would use it?

 

[Peter Nachtwey]

The DDV instruction should be used instead of the DIV instruction in many cases. A good example of where the DDV instruction should be used instead of the DIV instruction is when scaling and after a multiply or a multiply and add.

Try this
mulitply 2000 x 20
then divide by 100 using a DIV instruction.
the do the same using a DDV instruction.
Which one works?

 

[Ron Beaufort]

you can also find a few specific examples in Part 2 of my "Scaling with y=mx+b" papers available from the Sample Lessons page of my website ...

the discussion you're looking for starts near the end of Page 28 (Adobe page 4 of 17) and Figures 14, 15, and 16 demonstrate some DDV programming examples ...

 

[Paul B]

Cool thread! Today after reading about the DDV instruction here:
http://www.plctalk.net/qanda/showthread.php?t=55026

I opened Logix500 and read the instruction help for DDV. So this thread was very timely for me and probably others who had not heard of or used a DDV.

Ron your paper was great, thanks for the help. I'm still chuckling about this:

the instructor for that one was a trim little lady ... you could have sold tickets just to watch her erase the board ... I paid attention in statistics class ...