3 Phase Motor Start Up Logic

[Guest]

HI EVERONE IF ANYBODY REVIEWED THE ABOVE CODE THEN CAN YOU TELL ME THE PURPOSE OF THE RUNG 002 IN THE LADDER 2 WHAT DOES IT DO( BIT0/15) . MUCH APPRECIATED. MIKE

[Chris Elston 79]

It's just a bit you can stick anywhere in your logic to prevent something from coming on. I use it alot when I am debugging a machine, and I don't want to break the machine, so I stick a NEVER ON bit in the rungs I am not ready to debug yet, to prevent them from going true or turning an output on I am not ready to watch come on yet. Just in case.....And then the ALWAYS ON bit I use to branch around conditions that are not true yet like internal bits that you can not force on. Plus, when I am done debugging, I search for the NEVER ON and ALWAYS ON bits to make sure all my forces or overrides are out of the program. Hope that helps.

[BobLfoot 302]

Chako explains the bit quite well. What he fails to mention is that placing the coils for the ALWAYS ON and NEVER ON bits in early rungs like 001 and 002 lets all know they are in use. We also will set aside a portion of a B File {Allen Bradley} or create a Debug Tag of type DINT for use as debug timing bits. These debug bits can switch portions of logic in and out without the need to edit,, test and compile.

[forqnc 2]

Are you saying assign a B file so when debugguing you can set a bit to 1 or 0 while running to debug? Sorry sometimes I need things simplified

[TConnolly 13]

forgnc, you can either reserve a word or words in the B bile, for example B3:100, which gives you 16 debug bits per word or you can create a dedicated B file for debugging. Its a personal preference. (WOW, this is an old thread resurrection.)

[BobLfoot 302]

Yes I sometimes reserve an entire B file for debug flags. And yes Alaric I was reading the archives and found this interesting.

[forqnc 2]

Thanks Alaric and BobLfoot, I guess we are never to old to learn new Tricks.

[BobLfoot 302]

Einstein is rumored to have not known his own phone number because "I never memorize anything I can look up". Applying this logic I never create a wheel, I can borrow from someone else.