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Function call

Created by: NPkumar at: 5/14/2010 7:41 AM (1 Replies)

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5/14/2010 7:41 AM	Rate (0)
NPkumar Posts: 12 Rating: (4)	Hi, How to write some Bits & Bytes in datablock by using function call. Example:- Function is configured for 2 Input variable & 1 output variable. 1st input variable is programmed to set the Output variable 2nd input variable is programmed to Reset the Output variable 1st input varaiable is configured i0.0 2nd input varaible is configured 10.1 Output variable is configured shared DBnn.DBx0.0 If I make 1st input TRUE then it is setting the Output i.e DBnn.DBx0.0, But after I make 1st input FALSE immediately Resetting the Output i.e DBnn.DBx0.0. Why it is not retaining the Set command in shared DB??? If I configure Marker Bit It is Retaining, why not in Shared DB????
NPkumar Posts: 12 Rating: (4)
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5/14/2010 9:05 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 12/29/2025 Posts: 3052 Rating: (1062)	Hello NPkumar while thebehaviour that you observed may seems strange, it can actually be expected. The golden rule for FC OUT parameters is that they MUST be assigned (written to) inside the FC every time the FC is called. The fix in your case is either: - Change the OUT to an IN_OUT OR - Leave it as an OUT and find a way toutilise a Coil(=) assignment instead of an S/R (and make sure you execute that command every FC call, i.edo NOT have any jumps over it). You can find out more in the FAQ below and I hope this helps: Why does a function sporadically yield inaccurate return values in OUT parameters and what should you watch for when you assign input and output parameters?
	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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