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indirect access for instance DB

Created by: pici_c at: 6/27/2011 8:31 PM (9 Replies)

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6/27/2011 8:31 PM	Rate (0)
pici_c Posts: 80 Rating: (2)	Hi all! I am trying to use indirect instance DB accessing, but without any succes. My problem is simple, but I do not now the right syntax for it: What I am trying to do is: I have an FB1. I have 3 instance DB to it: DB1 DB2 DB3 the program would be like: L 1 T #temp call FB1, db[#temp] L 2 T #temp call FB1, db[#temp] L 3 T #temp call FB1, db[#temp] is this possible?? Thanks: Coyote
pici_c Posts: 80 Rating: (2)
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6/27/2011 8:38 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (996)	pici_c Hi all! I am trying to use indirect instance DB accessing, but without any succes. My problem is simple, but I do not now the right syntax for it: What I am trying to do is: I have an FB1. I have 3 instance DB to it: DB1 DB2 DB3 the program would be like: L 1 T #temp call FB1, db[#temp] L 2 T #temp call FB1, db[#temp] L 3 T #temp call FB1, db[#temp] is this possible?? Thanks: Coyote No.
IBN-Service Posts: 8946 Rating: (996)
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6/27/2011 11:51 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/24/2023 Posts: 6821 Rating: (1349)	Please check the following links: How do you create and update multiple instances? Information about "Calling blocks and functions" Regards
	Demo Channel on Youtube
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6/28/2011 5:05 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 9/23/2023 Posts: 2987 Rating: (1034)	Hello pici_c while your intended way is not possible, there is a "workaround" to achieve what you are trying to do and its principle isas followed: 1.) Open the desired Instance DB prior to the call of the FB (e.g. via OPN DB [#temp] in your case). 2.) Supply all IN's and IN_OUT's of the the FB by directly putting their values into their rightful place of the just opened Instance DB. 3.) Call the FB without Instance DB via the "UC" command. 4.) Copy the results from theInstance DB's IN_OUT and OUT FB parameterinto whatever variable you need to have them. Attached is a pic that should help in making sense out of the above. P.S: The example callsFB2 fromFB1 and also shows how to restore FB1'sIDB once the call of FB2 is finished aswell ashow to manipulate DB Registers (you may not need all of this, theexample merely shows the principle and I "stole" it from an entry of minein the German forum some time agowhen a similar question was posted). A Multi Instance Solution would of course be the elegant way to do the same and may be the solution for you too. I hope this helps Attachment UC FB call example.jpg (398 Downloads)
	Last edited by: fritz at: 6/28/2011 10:10 AM typos Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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6/28/2011 6:53 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (996)	Hi Fritz, your post is great like usual. But do you think so much work doreally make sense? In that case I would prefer an FC with a DB as Input - Parameter. Mutch easyer, right?
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6/29/2011 11:44 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 9/23/2023 Posts: 2987 Rating: (1034)	IBN-Service But do you think so much work doreally make sense? Let's put it that way Juergen, I never had a real need to use this method in an actual project. It is however a way to achieve what pici_c wants to do (I could only speculate on the"practical" reasons he may have to do so). IBN-Service In that case I would prefer an FC with a DB as Input - Parameter. Mutch easyer, right? I suppose so, but pici_cwould then have to convert his FB to an FC which he may not be able to do if it is for example a protected FB from the Library or SFB. Apart from the required manual creation of the DB structure it would also meanthat partial addressing is required inside the FC to access the DBvariables so it may end up being more work and/or becomingless maintable as a result. I guess the real question is why pici_c (thinks he) needs to do the indirect Instance DB opening, perhaps he can shed some light on it?
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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6/30/2011 8:29 PM	Rate (0)
pici_c Posts: 80 Rating: (2)	Thanks for the ideas! The real problem i had was that I use several quite the same FC-s in which I call the FB41 (CONT_C Simatic) block with unique instance. To minimalize the variables that have to be changed (when I create a new FC) I wanted to put an input integervariable in th FC, which would tell which instance has to be used for the PID. This is not possible (except the solutions mentioned above, but they are quitecrazy, sorry ). My final solution is using an FB,puttinga PIDinstance into the stat variables, so I always call the same instance, only the "parent" FB is changing.. I hope you understand what I mean.. Coyote
pici_c Posts: 80 Rating: (2)
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7/1/2011 8:23 AM	Rate (0)
IBN-Service Posts: 8946 Rating: (996)	pici_c ... I hope you understand what I mean.. Coyote To be honest, no. Why? If you like to use differentparameterset for same FB/SFB41, just suply a VERY I-DB with different template - DB of FB41: Before FB41 call, copy the template-DB into I-DB. Call FB41 with same I-DB any time After FB41 call, save the I-DB in your template-DB. You just need an indirect adressed copy function, use SFC20. Amount of template - DB is just limited by CPU memory.
IBN-Service Posts: 8946 Rating: (996)
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7/1/2011 12:49 PM	Rate (0)
pici_c Posts: 80 Rating: (2)	"just suply a VERY I-DB with different template - DB of FB41" now i don't understad what you say. How do I do that? what is a VERY I-DB? how doI create it? (the other part I understad (using the SFC20)) One more question: can I determine the number of the FC inside the FC. Is there an instruction for that? thx
pici_c Posts: 80 Rating: (2)	Last edited by: pici_c at: 7/1/2011 1:24 PM
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7/1/2011 6:07 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (996)	pici_c "just suply a VERY I-DB with different template - DB of FB41" ... Sorry for my bad explanation. I want to say that you have to use your FB with only ONE instance -DB (I-DB) This I-DB (=DI) will be get values from another DB with same structure. pici_c ...One more question: can I determine the number of the FC inside the FC. Is there an instruction for that? thx Oh.... I dont think so. You can read the number of open DB and DI, but not No. of FC or FB....
IBN-Service Posts: 8946 Rating: (996)
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