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Using Datablocks for logic

Created by: markallinson at: 6/18/2010 10:44 AM (8 Replies)

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6/18/2010 10:44 AM	Rate (0)
markallinson Regular Member Joined: 12/2/2008 Last visit: 11/30/2023 Posts: 20 Rating: (0)	Just a quickie, Is there any reason why I shouldn't use datablocks in my logic? I'm using datablocks as a means of data exchange with a remote system over ethernet. So I've now started using some of the datablock points in my logic and it occured to me that this may or may not be a good idea? Thanks in advance Mark

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6/18/2010 11:01 AM	Rate (0)
UMENCHO Diamond Member Joined: 3/21/2006 Last visit: 10/4/2024 Posts: 10229 Rating: (1181)	Hello Mark, Why don't we use DBs? My way is - all I/Os are transfered first to the DBs and then work only with DB values like real I/O. For the moment I don't have any troubles with this. This helps me if in future I need to use the same project (to implement it) in other hardware. With other words, the software is going to be more "universal". Best regards, Hristo Mihalev

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This contribution was helpful to 1 thankful Users Ayman Elotaify

6/18/2010 11:11 AM	Rate (0)
Aristotelis Posts: 147 Rating: (34)	Hi markallinson Is there any reason why I shouldn't use datablocks in my logic? There is absolutely no reason NOT to use data blocks in your program. The use of data blocks results in a very "clean" & structured program, that everyone is happy to read, extend & debug. Don't take my word for it, but I do not know of an alternative (except maybe by using bit memory -M- but it is much more limited) to have your data stored. Keep in mind retentivity though, and the differences between each memory type. For more info, I would suggest you take a look in SIMATIC S7-300 CPU 31xC and CPU 31x: Technical specifications manual, ch. 4. Hope this helps
Aristotelis Posts: 147 Rating: (34)
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6/18/2010 12:33 PM	Rate (0)
markallinson Regular Member Joined: 12/2/2008 Last visit: 11/30/2023 Posts: 20 Rating: (0)	Superb! Thanks for your replies guys. This confirms I'm doing things the correct way yippee

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6/18/2010 3:04 PM	Rate (2)
Darius Platinum Member Joined: 9/28/2005 Last visit: 8/27/2024 Posts: 2957 Rating: (242)	Hello, Some time ago I've donloaded good manual from Siemens site, but now I can't find it. I'll try to attach it here. It could be useful in your case. Don't know why Siemens removed it from its site. Attachment Proent_e.pdf (145 Downloads)
	Best regards, Darius
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This contribution was helpful to 2 thankful Users AMAZINGAHMED Aristotelis

6/19/2010 7:21 AM	Rate (0)
Arpit Posts: 49 Rating: (1)	Thanks Darius for the document. It's really helpful...
Arpit Posts: 49 Rating: (1)
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6/19/2010 9:42 AM	Rate (0)
cdrshort Bronze Member Joined: 9/6/2008 Last visit: 3/29/2024 Posts: 134 Rating: (16)	very good info. thanks darius
	Last edited by: cdrshort at: 6/20/2010 10:22 PM http://electrotech-techblogg.blogspot.gr/
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6/21/2010 12:46 PM	Rate (0)
Aristotelis Posts: 147 Rating: (34)	Hi Darius Darius Hello, Some time ago I've donloaded good manual from Siemens site, but now I can't find it. Where in the world are these things hidden? Thanks a lot Darius.
Aristotelis Posts: 147 Rating: (34)
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6/21/2010 1:54 PM	Rate (0)
bit7 Experienced Member Joined: 7/26/2008 Last visit: 9/27/2024 Posts: 100 Rating: (19)	Hi Mark, as a principal I use data blocks for all my variables, use flags (m memory area) as a scratch (temporary) memory area and in FBs use tempory area (local data). Structures in data blocks can be used to organise data logically. It is also unlikely that another programmer will change anything in a data block, he would simply create a new one. The only down side is that accessing data blocks takes more space and is slower. When this becomes an issue I copy bits from data blocks as DWs to the temporary area, perform the logic and copy the bits back. Hope this helps.

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