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UDT as static or Temp in an FB from an Optimized DB

Created by: Schrien at: 9/19/2014 10:59 AM (8 Replies)

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9/19/2014 10:59 AM	Rate (0)
Schrien Posts: 18 Rating: (0)	Hello, I have an optimize db (DB_TRS_01) with one UTD. This UDT contains somt int's, booleans an one Array[1..20] of struct. I have a CPU 1516-3 PN/DP and i'm using TiaV13 update4. I want to use these variable in several FB's as an input DB_ANY. -> i_DB (data typ=DB_ANY) With this input i want to move the hole UDT in a Temp or a Static so i can use it in my code. I'm working in STL i don't now how. I tryed to use ReadFromArrayDB but it doen's work. Can someone help me please?
Schrien Posts: 18 Rating: (0)	Last edited by: Schrien at: 9/19/2014 11:09 AM
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9/19/2014 2:51 PM	Rate (0)
William_B Posts: 5225 Rating: (1198)	Hi there, You are creating much problems for yourself by trying to do what you ask in STL. Do you know you can mix STL and LAD in the same code block? The UDT is handled better with the MOVE instruction in LAD. This is only possible with S7-1200 and S7-1500 PLCs. Please see the example attached... The example does anything in particular, but shows the concepts you need (I think). Does this help you? w Attachment Visual Clue_Using UDT to pass data (LAD).jpg (831 Downloads)
William_B Posts: 5225 Rating: (1198)	Last edited by: William B. at: 9/19/2014 2:52 PM format
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9/19/2014 4:33 PM	Rate (0)
Schrien Posts: 18 Rating: (0)	This is somthing i already know.. But i want to have the DB himself as input for the FC. And not the UDT from the DB This is because i need that number later in my program... So i want the DB as input. and with that input opening the DB and get out the hole UDT. Is that possible?
Schrien Posts: 18 Rating: (0)
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9/19/2014 4:57 PM	Rate (0)
William_B Posts: 5225 Rating: (1198)	Schrien This is somthing i already know.. But i want to have the DB himself as input for the FC. And not the UDT from the DB This is because i need that number later in my program... So i want the DB as input. and with that input opening the DB and get out the hole UDT. Is that possible? ..okay It would be most helpful if you made a paper drawing of what you want to do. Because I do not understand the WHY, it is difficult for to picture what you need. If I understand you now.. You wish to be able to pass on the "100" of DB100 so that you can do DB(100) later inside your FC. If I understand the indirect addressing that you need, you will have to have non-optimised DB for it to work right. [LINK] I can however not understand why you want to do that.. unless you want to handle not only one type UDT or have several UDT to handle. In my example there is a UDT called in the IN/OUT parameters. You can do the same for an FC. For memory usage the IN/OUT handles the UDT variable as if indirect access. The IN/OUT is not a copy but a pointer. Another alternative you can look at (S7-1500) is the use of VARIANT. This will handle what you want to do.. but yo will have to play around with how it is done. IMHO I would not suggest to take this road of making a cure-all solution. Indirect addressing cause all sorts of issues in the field for in-house technicians. Probably someone else will have other ideas. (HINT: Jens_App, huggy_d1) w
William_B Posts: 5225 Rating: (1198)
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9/19/2014 5:35 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 1/17/2025 Posts: 15541 Rating: (2465)	I completely agree with William B. You cannot do what you want with an Optimized DB---unless!!! you do the following (and these are typically impractical): 1. Reverse engineer your solution since Siemens is not going to tell you the answer on how the data is really stored in that UDT. Send the UDT via DB to something in a PUT block to another DB in another PLC that has that DB set as non-optimized. Now change values in the source UDT values (watch table). View the watch table in the receiving PLC and now you see where the various values are coming in. Reverse engineering completed. 2. Never ever update your PLC firmware after you do this. Never ever update your portal software after you do this as step 1 will be required again for either of these to validate these assumptions. 3. Now that you know the absolute addressing, you can use it within the plc program just as if they were configured as absolute. Just document the program. I would offer an alternative as hinted at above. Make TWO DBs. Put the same values in both DBs anywhere you assign a value to any tag in the UDT. In this way, you always have the same data in both and have the flexibility to use the data either way. If you need to process internally, use the optimized data. If you need to send it out in a predictable manner, use the non-optimized version. Yes, I know this is a little strange, but you are trying to get around the very nature of what Siemens put into TIA Portal and the optimized access option, so what did you expect?
	science guy
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9/22/2014 8:01 AM	Rate (0)
Schrien Posts: 18 Rating: (0)	Thanks huggy_d1 and Willian B. It seems to be very complicated the way to use to DB's. And even I can't use it because I want to increase the CPU time and his memory. If I need everywhere 2 DB i don't think it helps. So I keep on going with the UDT. Thanks a lot.
Schrien Posts: 18 Rating: (0)
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9/22/2014 8:26 AM	Rate (0)
William_B Posts: 5225 Rating: (1198)	Hi... it is me... William.. I can bet that you do not waste so much memory with non-optimised DB that it would matter. Consider that the "Program Info" does not give the correct Load Memory size at first (under TOTAL). This have to be set by you (I do not know why). Play around with optimised vs non-optimised to see the statistics in "Program Info". If the numbers are acceptable, let someone guide you through alternatives. - - just as to keep your options open on using PEEK/POKE in SCL. Thanks for the feedback & good luck with your project w
William_B Posts: 5225 Rating: (1198)
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9/22/2014 4:33 PM	Rate (0)
Schrien Posts: 18 Rating: (0)	Sorry Willliam, After a day testing i have it! Look at the picture. Now i have my UDT as a Temp in my FB. First from db_any to Variant, then from variant to UDT. But now i have a second question. You can see i can get my array in the UDT symbolic(red rectangle). Is it also possible to get it like DBW0 or something like that? This is what i want because i have a lot loops in STL with this kind of pointers to the array. If I need to change al these its gone be a lot of work. Thanks Attachment Untitled.jpg (534 Downloads)
Schrien Posts: 18 Rating: (0)
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9/23/2014 9:08 AM

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Jens_app

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Dear Schrien,

please let me quote a part of your first post:

"I have an optimize db (DB_TRS_01) with one UTD."

Now let me quote siemens help file:

"Data blocks with optimized access have no fixed defined structure. The declaration elements contain only one symbolic name in the declaration, no fixed addressing within the block. The elements are saved automatically in the available memory area in such a way as to make optimal use of this area's capacity.
Variables in these data blocks can only be addressed in symbolic form. For example, you access the "Fill Level" variable in the "Data" DB as follows:

"Data".Fill Level"

If you want to use absolute addressing (DB1.DBW0)you should havea data block with standard block access. So what you are trying to do is not possible.

Since you are using pointers I guess you gave up the idea of using optimized data blocks.

Ithink following thread will be quite useful to you, please take a look at it, I'm sure it will answer some of your questions:

Technical Forum: Extended instruction handling Variant pointer in TIA V13 - S71500.
...new functions for handling variant pointers in TIA V13. See attached PDF. * DB_ANY_TO_VARIANT : Create a variant pointer to a DB. * TypeOf...VARIANT contend MOVE_BLK_VARIANT: Move whole VARIANT (no parti...
STEP 7 (TIA Portal)

2014-05-12

ID: TF523973

Kind regards,
Jens

Keep it simple and on-topic.

A simple straight-to-the-point answer is often of more quality than a complicated one.

Created by: Schrien at: 9/19/2014 10:59 AM (8 Replies)

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Last edited by: Schrien at: 9/19/2014 11:09 AM

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Last edited by: William B. at: 9/19/2014 2:52 PM

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