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Step 7 SCL temporary variable initial value

7/12/2014 12:54 AM	Rate (0)
davidengr Posts: 15 Rating: (0)	Are temporary variables in SCL gauranteed to be initialized to zero or are there initial values undefined? Could they be initialized to some non-zero value?
davidengr Posts: 15 Rating: (0)
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7/12/2014 6:27 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 1/5/2026 Posts: 6892 Rating: (1368)	davidengr Are temporary variables in SCL gauranteed to be initialized to zero or are there initial values undefined? Could they be initialized to some non-zero value? Hello, For functions and function blocks that are created by SCL, it is necessary to initialize temp variables at the beginning of block.Initial values of those parameters are undefined in runtime and they are places to keep the intermediate calculated values. For OBs, some temporary variables are written by CPU's OS itself. I hope this helps, Hamid Hosseini
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This contribution was helpful to 3 thankful Users William_B Mahesh N C-3PO

7/13/2014 10:23 PM	Rate (0)
lad_stl Posts: 101 Rating: (0)
lad_stl Posts: 101 Rating: (0)
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7/18/2014 10:37 PM	Rate (1)
beserb Posts: 52 Rating: (4)	NEVER read a temporary variable before writing to it in a function. This is because temporary areas are common memory areas and used by every block (OB, FB, FC). If you need some fixed values (non-zero or zero) you can use CONSTANT definition in SCL.
beserb Posts: 52 Rating: (4)
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7/19/2014 11:38 AM	Rate (0)
William_B Posts: 5225 Rating: (1204)	beserb NEVER read a temporary variable before writing to it in a function. This is because temporary areas are common memory areas and used by every block (OB, FB, FC). If you need some fixed values (non-zero or zero) you can use CONSTANT definition in SCL. Thank you - that is very important. Note that this applies to all programming languages and not just SCL. This applies to all user defined temporary variables, but as stated by our friend hdhosseini, some OBs have system created temporary variables that are actaully asigned values by the OB. ..now the hairs are split in two [wink] w
William_B Posts: 5225 Rating: (1204)
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