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9/7/2011 8:37 AM | |
Posts: 2348 Rating:
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Really nice:^) I didn't know this feature on turning multi-instance off |
9/7/2011 2:13 PM | |
Joined: 10/7/2005 Last visit: 9/5/2024 Posts: 3018 Rating:
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To tell you the truth Aret, I never really thought about this before. One advantage I can see is though that you should be able to freely use AR2 since it isnot used in a FB without Multi Instance capability(just like an FC never uses AR2) Secondly, since the AR2 usage ina FB with Multi Instance capabilityis needed forall accesses toits Block parametersand STAT's (viaso called "register-indirect area internal addressing"), anFB without Multi Instance capabilitywill (should)execute a tad bit faster (haven't tested this though). Also,if you need to do indirect addressing to access STAT variables, you will NOT have to take the offset in AR2 into account when creating the pointer ina FB without Multi Instance capability. Another rather "useless" advantage is that you can alsoforego symbolic addressing of STAT variables and shoot directly for the DI address(e.g L DIW 2, T DIB 14, "useless advantage"becauseIdo NOT want to encourage this kind of addressing). Having said all the above and listed all possible advantages that I at least can think of.this, I have NOT had the need yet to take advantage of them myself (perhaps one day I will). Idogenerally prefer to create a Multi Instance capable FB which has the rather obvious advantage that it can be called asa Multi Instance. Juts for completeness, the link below has some more info on the subject of FB's and AR2: In which operations does STEP 7 overwrite ACCU or register contents? |
Last edited by: fritz at: 9/7/2011 2:17 PMtypos Cheers |
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