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Why some FC has the RETVAL?

Created by: avafab at: 4/20/2012 8:29 AM (8 Replies)

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4/20/2012 8:29 AM	Rate (1)
avafab Posts: 83 Rating: (1)	Hello guys! When I call main FCs in the OB1, most of them don't need a retval, but some of them ask me to fill the retval.. why? what does it mean? thank you
avafab Posts: 83 Rating: (1)
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4/20/2012 8:37 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 1/8/2025 Posts: 6858 Rating: (1366)	avafab Hello guys! When I call main FCs in the OB1, most of them don't need a retval, but some of them ask me to fill the retval.. why? what does it mean? thank you Hello avafab, "ENO" and "return value" are your feedback of how the function processed in the runtime.Please,be familiar with the functionality and use them for trouble-free program execution. Best regards, Hamid Hosseini Attachment diagnostics.zip (639 Downloads)
	Demo Channel on Youtube
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4/20/2012 8:53 AM	Rate (0)
avafab Posts: 83 Rating: (1)	but why some FC has a ret val (FC that I develop!!) and some else don't have?
avafab Posts: 83 Rating: (1)
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4/20/2012 9:05 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 1/8/2025 Posts: 6858 Rating: (1366)	avafab but why some FC has a ret val (FC that I develop!!) and some else don't have? Hello , This "RET_VAL" is only an output of a function which are often complex and professional programmers provide that for ease of users in case of troubleshooting.You can test your FC by defining such an output and transfer values to it in case of some events and then monitor the result. Best regards, Hamid Hosseini Attachment return.zip (626 Downloads)
	Demo Channel on Youtube
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5/4/2012 9:39 AM	Rate (0)
avafab Posts: 83 Rating: (1)	Ok, I know the principle of RET_VAL I develop a FC with my own code in LAD and I don't specify that I want a RET_VAL I go to OB1 and make a simple CALL to this FC and it ask me to fill RET_VAL witha variable my question is: why? maybe because I used some system functions that need a RET_VAL?
avafab Posts: 83 Rating: (1)
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5/4/2012 12:05 PM	Rate (0)
yy1 Gold Member Joined: 3/24/2009 Last visit: 7/9/2024 Posts: 535 Rating: (112)	avafab my question is: why? maybe because I used some system functions that need a RET_VAL? Dear avafab, if you didn't define the datatype of the RET_VAL in your FC, I can see no reason, why you should need this variable. Please check the interface - to be sure, you can set the datatype of RET_VAL to VOID. The RET_VAL of the used system-function sould not matter - as long as you don't write the result to your own RET_VAL. Best regards, yy1

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5/4/2012 2:15 PM	Rate (0)
avafab Posts: 83 Rating: (1)	I agree with you! I checked the interface too, a temp variable is present "RET_VAL" but it is not possible to delete it, it seems that siemens put it as default!! strange thing...
avafab Posts: 83 Rating: (1)
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5/4/2012 2:25 PM	Rate (0)
SolutionFinder Posts: 559 Rating: (87)	Dear avafab, Please find the attached screen shot in which we have created FC. But there is no RET_VAL here. so u are getting ret_val in your case. If u make FC, Then Into In,Out parameters u must have to define values during Call. But if u make FB then u can left blank instead of defining all paramaters during call of that FB. Attachment s7_300.JPG (808 Downloads)
SolutionFinder Posts: 559 Rating: (87)
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9/18/2021 8:32 PM	Rate (0)
Basketballer Experienced Member Joined: 2/20/2018 Last visit: 1/7/2025 Posts: 46 Rating: (0)	If you change VOID type to for example INT type concerning the variable with the same name as your FC function name, than the Ret Val will be non-void and will be visible on outside. Regards.
	Adam
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