Old dogs can learn new tricks

I realize that binary, hex...etc is nothing new but I have had many questions about how the data files actually work in ladder logic. I knew that PLCs read and write using binary but I wasn't quite sure how the processor adds, subtracts the N7 data word and move the data to the preset destination plugged into the instruction.
That was until I read a post from back in 2003 about Two's Complement formatting. The concept and arrangements blew my mind because they were so easy to understand, as well as, calculate (on a small scale of course), but nevertheless, I am beginning to understand more and more about how the computer thinks, thus making it easier to actually know what's going on during a scan rather than scratching my head and wondering.

I just wanted to share this with you all, and to say thank you for helping all of us who have been struggling with these crises.
Regards,
Jay

You have a link to the thread?

http://www.academia.edu/288642/The_Formal_Specification_of_a_Microprocessor_Instruction_Set
Here is a good paper on the microprocessor instruction set. Brings back memories...

Regards,
Garry
http://www.accautomation.ca

P.S. Here is a post on a different way of programming:
http://accautomation.ca/building-a-plc-program-that-you-can-be-proud-of-part-1/

This is the one I found Snap25. The member's username is [highlight]nehpets[/highlight]
http://www.plctalk.net/qanda/showthread.php?t=83870&highlight=Two's+Complement

Learning about the Z80 CPU instruction set back in the late 70's help me a lot with understanding PLC CPU math. It's very similar to the mnemonics you see in PLC Direct code.

I am beginning to understand more and more about how the computer thinks, thus making it easier to actually know what's going on during a scan rather than scratching my head and wondering.

Click to expand...

It won't be long now until you get passed the baton to carry on the good name of this site.

When I teach basic PLC's I always begin with how they work, including: How binary works and how binary is used to build Hex and touch on Octal for legacy systems and certain Automation Direct products. ;-)

Someone has a signature that says it well:
"There are 10 kinds of Engineers, those who understand Binary and those who do not."

Someone has a signature that says it well:
"There are 10 kinds of Engineers, those who understand Binary and those who do not."

Click to expand...

There is also this one:

Why do programmers get Halloween and Christmas mixed up?
Because 31 OCT equals 25 DEC.

This site has overstuffed me with knowledge. PLCs can do way more than the things that they usually teach you in a trade school program. I would have never known what a MOV command did or how data blocks worked if I wouldn't have found this place. Even so on more subjects relating to controls period. I recently got some amazing, straight forward answers about PID loops, as I am just beginning to learn them.

This place is just awesome

Hey Lancie, I appreciate the vote of confidence! I'm beginning to tip toe into the advanced side of ladder logic, and oh boy.....it is a little difficult to keep up with the files and bits...etc.
I do hope to be good enough one day to be able and carry on the name of this site, but for now I will listen to the masters on here and try to learn the ways of the force

There is also this one:

Why do programmers get Halloween and Christmas mixed up?
Because 31 OCT equals 25 DEC.

Click to expand...

Good one Steve!