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Runtime in microseconds

Created by: gjwebber at: 1/12/2012 10:39 AM (4 Replies)

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1/12/2012 10:39 AM	Rate (0)
gjwebber Posts: 18 Rating: (0)	Hi all, I was looking through a PDF linked on this site, titled "System Software for S7-300/400 System and Standard Functions - Volume 1/2". There is an SFC listed there (SFC 78) which allows you to extract the runtime information of a specified OB in microseconds, which is exactly what I need. The only problem is, we are using 319 processors and it seems like it isn't a standard function on them. Is it a 400 only function? Is there any way we can get the runtime information of OB1 in microseconds? I can see there is a millisecond value stored in OB1 itself, but that's not good enough in this instance. Thanks for any help, Gareth
gjwebber Posts: 18 Rating: (0)
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1/18/2012 2:00 PM	Rate (0)
Cicero Gold Member Joined: 10/10/2005 Last visit: 3/16/2023 Posts: 1909 Rating: (132)	Hello, you can insert the SFC78 from the libraries and is apply also for the CPU319. Open the FBD, STL or the LAD editor and set the view "view > Overviews". The SFC78 you will find by "Libraries > Standard Librariy > System Function Blocks". Put the SFC78 per Drag&Drop in the editor for further programming. All further informations you will find in the STEP 7 onlinehelp. Mark the SFC78 and use the F1-tape. With best regards Cicero

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1/18/2012 2:39 PM	Rate (0)
gjwebber Posts: 18 Rating: (0)	Hi Cicero, Thanks for your reply, but unfortunately it is not possible to do what you suggest. SFB's and SFC's exist within the PLC, whether you use them in your code or not. They are not downloaded to the PLC with the rest of your program. If I try and use SFC78 in my code there are no issues until the program is downloaded. In the diagnostics window it then says that SFC78 is missing. It seems silly that a PLC which is so fast (our program runs in OB1 at about 4ms) can only provide a resolution of 1ms, but that's the way it's starting to look. Any other info would be greatly appreciated! Thanks, Gareth
gjwebber Posts: 18 Rating: (0)	Last edited by: gjwebber at: 1/18/2012 2:41 PM
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1/19/2012 8:30 AM	Rate (0)
Cicero Gold Member Joined: 10/10/2005 Last visit: 3/16/2023 Posts: 1909 Rating: (132)	Hello, I'm not sure in this case. There are no hints in the online help that is only for S7-400. I recommend to update the firmware version of the CPU319. See the link: http://support.automation.siemens.com/WW/view/de/44442927 If this not successful, ask the customer support (hotline) from Siemens. See the link for make an service request: http://support.automation.siemens.com/WW/view/de/38716036 With best regards Cicero

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1/19/2012 9:37 AM	Rate (0)
gjwebber Posts: 18 Rating: (0)	It looks like I'm out of luck. The CPU-31x instruction set doesn't list SFC 78 "OB_RT" at all, whereas an instruction set I found for various CPU-400 processors does list it. Also, looking through the change notes in slightly more recent versions of our CPU firmware there is no mention of any SFC additions (2.8.0 --> 2.8.4). Do you think there are any other solutions? Thanks, Gareth
gjwebber Posts: 18 Rating: (0)
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