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Stantheman
February 24th, 2003, 08:06 AM
Help!!!!!!!
Can anybody explain to me the concept of EDDI.
I have struggled for hours on the web!
Hopefully somebody can help.
Thanks.

Allen Nelson
February 24th, 2003, 09:01 AM
Do you have a link on the web to share?

The only EDDI I could find in 3 minutes of searching was for "Error Detection by Duplicated Instructions", which has duplicate programs running concurrently and comparing the results to the core program, to verify that no bits are accidently flipped during the program execution due to bad memory locations.

Not suitable for PLCs (although it makes you wonder just how immune to corruption the little beasties are. I take it as gospel that a -( )- instruction sets a memory location to the value I expect it to be when I do a -| |-. Or, for that matter, when the PLC is executiong its program, that it doesn't accidently read -|/|- for one scan when I wrote -| |-.

But you've got to believe in something.... I believe I'll have another drink... (-Groucho Marx)

Guest
October 18th, 2004, 05:07 AM
you can find more information on EDDI here..

http://www.pspt.fi/kirjasto/opinnayt/abstrakti/abstrakti.tewa2002_MustonenTeemu_eng.pdf

dchartier
October 18th, 2004, 09:29 AM
Hello, Stantheman;
Siemens used to have a specialized version of their SFC programming software for the S5 PLCs called Graph5-EDDI. You could find the manual on the Siemens website as Graph5_V3, or by doing a search on EDDI. I'm don't remember how far they went to explain the EDDI theory, but you would find an actual implementation of dynamic error diagnostics.
Hope trhis helps,
Daniel Chartier

dash
October 18th, 2004, 12:34 PM
I managed to find a book with a short (very short) chapter on the subject. I should have it in a couple of days & I'll let you know if there is any usable information. The books title is "Programmable Controllers: An Engineer's Guide". Most likely useless, but I'll let you know.

Darren