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SET and CLEAR

Created by: nbk at: 12/19/2009 6:22 PM (3 Replies)

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12/19/2009 6:22 PM	Rate (0)
nbk Posts: 197 Rating: (3)	Dear all, Under what circumstances do we use SET and CLR instructions? Could someone give a specific e.g? regards
nbk Posts: 197 Rating: (3)
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12/19/2009 7:33 PM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 9/2/2024 Posts: 703 Rating: (96)	Hello, that's a strange question... Normallythere's some task and somebody looks for the instructions/solution... If you look to the online help of these instructions you get the information what is used for. Imho it's pretty clear so it's used when you want to setthe RLO to 1 or 0unconditionally. There's already some example, here's another: if the block would be used in LAD/FBD you should set the BR bit at the end for the ENO output, this can be done by SET or CLR followed by SAVE instruction. The other possibility is use for the initialization of the TEMP variables. Regards Sydney
	Last edited by: Sydney at: 12/19/2009 7:34 PM
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This contribution was helpful to 1 thankful Users nbk

12/19/2009 11:24 PM	Rate (0)
nbk Posts: 197 Rating: (3)	Hello Sydney, Please see the attachment(screen shot) There's a reset within SET.........I find it little contradictory. regards Attachment NPAVScSt.jpg (500 Downloads)
nbk Posts: 197 Rating: (3)
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12/20/2009 2:55 AM	Rate (2)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 9/12/2024 Posts: 3020 Rating: (1054)	nbk ...There's a reset within SET.........I find it little contradictory. Hello nbk I see where the confusion comes from. A "SET" command sets the RLO (Result of Logic Operation) to "1" (note that the "SET" command stands by itself and is not followed by an address as its sole purpose is to set the RLO to 1). A "S" or "R" command on the other hand do their "job" (setingor reseting of an address) IF the RLO is "1" (and must be followed by an address like Memory bit or Output etc.) . Your example logic in OB100 does as such works as followed: SET // "set" RLO to "1" SM 125.4 // "set" M 125.4 to "1" (since RLO is "1") R M 125.2 // "reset" M 125.2 to "0" (since RLO is "1") S M 125.3 // "set" M 125.3 to "1" (since RLO is "1") Using "SET", "CLEAR" and "="it could also be written like this: SET // "set" RLO to "1" =M 125.4 // "assign" RLO status to M 125.4 (e.g. M 125.4 ="1") = M 125.3 // "assign" RLO status to M 125.3 (e.g. M 125.3 ="1") CLEAR // "reset" RLO to "0" =M 125.2 // "assign" RLO status to M 125.2 (e.g. M 125.2 ="0") I hope this helps
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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This contribution was helpful to 7 thankful Users how come Sydney Denker nbk plsmocke Ctrller xplod_pencil

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