9/6/2012 1:18 PM | |
Joined: 4/24/2006 Last visit: 4/25/2024 Posts: 8613 Rating: (1147) |
Hello @Nick, Try to use the SystemFunction: SFC20 Blkmov. System Software for S7-300/400 System and Standard Functions Volume 1 and Volume 2 See chapter 3 Best regards, Wizard |
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9/6/2012 3:38 PM | |
Joined: 9/27/2006 Last visit: 4/25/2024 Posts: 12257 Rating: (2665)
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Hello Nick; The statement you refer to means that if the data in SRCBLK changes while you are processing the SFC20 (if the Profibus cycle writes new data to the slave at the same time SFC20 is called, for example) the accuracy of data sent to DSTBLK cannot be garanteed. On my experience I have never encountered such a problem, the Profibus cycle is independant of the PLC scan and access to each slave is counted in microseconds, so it would take a great coincidence for SFC20 to be requesting data at exactly the same timeslot that the slave is writing to the PLC memory. However, Wizard's last point is very important, as you cannot use an ANY pointer with peripheral addressing, i.e. PIWxxx or PQWxxx addresses outside of the input/output image tables. As per your last screencapture, the addresses show are used for aProfibus slave and seem to beperipheral addresses. So when you say SFC20 "seems to be working" as programmed now, just make sure the values you are reading are correct (changing with what the slave is actually sending). To test this, move the value of PIW522 to an MWxx of your choice and compare it in a VAT table with the first register of your DSTBLK. If they do not match, see the following FAQ for a workaround. http://support.automation.siemens.com/WW/view/en/22783999 Note that in the FAQ the authors are using S7German mnemonics, PEWxxxcorrsponds PIWxxx in English; PAWxxx is PQWxxx in English mnemonics. Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 9/6/2012 5:45 PMLast edited by: dchartier at: 9/6/2012 3:40 PM |
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9/6/2012 4:14 PM | |
Joined: 11/17/2010 Last visit: 11/25/2020 Posts: 81 Rating: (2) |
Thanks Guys! Case closed! Greets, Nick |
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