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M MEMORY

Created by: GaJEnDrA D S at: 6/9/2012 8:17 AM (12 Replies)

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6/9/2012 8:17 AM	Rate (0)
GaJEnDrA D S Bronze Member Joined: 8/9/2011 Last visit: 6/17/2023 Posts: 324 Rating: (19)	Hi everyone Is there any problem in using MD0 Instead of DBn.DBD0 ? coz its good for extracting part of address in case of M rather than DB Thanks :-)
	Last edited by: GAJENDRADS at: 6/9/2012 8:58 AM Last edited by: GAJENDRADS at: 6/9/2012 8:19 AM "Any intelligent fool can make things bigger, more complex. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.":):)
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6/9/2012 11:59 AM	Rate (1)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 9/21/2023 Posts: 1499 Rating: (220)	GAJENDRADS Hi everyone Is there any problem in using MD0 Instead of DBn.DBD0 ? coz its good for extracting part of address in case of M rather than DB Thanks :-) Hello Gajendrads, Check this FAQ - How in STEP 7 V11 can you access the unstructured data types bit-by-bit, byte-by-byte or word-by-word and symbolically?Hope this helps. So you can do the same in DB as in Bit Memory. In fact your Bit Memory is much less than the Data Block memory in size. Bit Memory typically can be used for flags, discrete alarms, etc. If you start using the Bit Memory (M) as Word or DWord, then you will be running short of memory very soon.
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6/9/2012 1:27 PM	Rate (1)
IBN-Service Posts: 8946 Rating: (996)	GAJENDRADS Hi everyone Is there any problem in using MD0 Instead of DBn.DBD0 ? coz its good for extracting part of address in case of M rather than DB Thanks :-) Yes, you can. It is no problem. Also, using M is mutch faster then DB. But numbers of M is limited more than number of DB data. Unfortunately, what Ganes said is only valid for the 1200 CPU, not for 300 or 400!
IBN-Service Posts: 8946 Rating: (996)
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6/9/2012 2:34 PM	Rate (0)
GaJEnDrA D S Bronze Member Joined: 8/9/2011 Last visit: 6/17/2023 Posts: 324 Rating: (19)	Hellow.. Thanks to S71200 i have left with with plenty of M memory (0--15534) unlike S7 200(0--32) Prominently it reduces the work memory to the great extent
	"Any intelligent fool can make things bigger, more complex. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.":):)
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6/9/2012 2:37 PM	Rate (0)
GaJEnDrA D S Bronze Member Joined: 8/9/2011 Last visit: 6/17/2023 Posts: 324 Rating: (19)	Hi Thanks for the information i was little worried about Execution speed.
	"Any intelligent fool can make things bigger, more complex. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.":):)
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6/9/2012 3:51 PM	Rate (0)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 9/21/2023 Posts: 1499 Rating: (220)	IBN-Service GAJENDRADS Hi everyone Is there any problem in using MD0 Instead of DBn.DBD0 ? coz its good for extracting part of address in case of M rather than DB Thanks :-) Yes, you can. It is no problem. Also, using M is mutch faster then DB. But numbers of M is limited more than number of DB data. Unfortunately, what Ganes said is only valid for the 1200 CPU, not for 300 or 400! Hello IBN-Service, Yeah memory slice is a little bit different for S7-300 and S7-400 in STEP 7 v11. For example, can't we access a Double Word of DB1.DBD0 as DB1.DBX0.0 (as a Bool) or DB1.DBB0 (as a Byte) or DB1.DBW0 (as a Word) ?? I think in this way we can access the Double word as either bool or byte or word in S7-300 and S7-400.
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6/9/2012 3:55 PM	Rate (0)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 9/21/2023 Posts: 1499 Rating: (220)	GAJENDRADS Hellow.. Thanks to S71200 i have left with with plenty of M memory (0--15534) unlike S7 200(0--32) Prominently it reduces the work memory to the great extent Hello GAJENDRADS, Which CPU (S7-1200) are you using? As of now 8192 bytesbit memoryis available in CPU1214C and CPU 1215C.
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6/9/2012 5:20 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 9/21/2023 Posts: 13714 Rating: (2240)	GAJENDRADS Hi everyone Is there any problem in using MD0 Instead of DBn.DBD0 ? coz its good for extracting part of address in case of M rather than DB Thanks :-) With the latest portal / s7-1200 firmware, you can access memory from the tag regardless of DB or M. MyTag.x0 is bit 0. MyTag.b0 is byte 0 of MyTag As for MD0, you might want to start at MD2 or 4 as the default system memory bytes MB0 & MB1 if your project uses them for first scan, clock bits, etc.
	science guy
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6/9/2012 6:25 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (996)	Ganes10 ...Yeah memory slice is a little bit different for S7-300 and S7-400 in STEP 7 v11. For example, can't we access a Double Word of DB1.DBD0 as DB1.DBX0.0 (as a Bool) or DB1.DBB0 (as a Byte) or DB1.DBW0 (as a Word) ?? Yes, you can, but unfortunately not symbolic but onlyabsolute. Or via P## operator and AR handling, what is not sovery nice / easy as the slice function of S7-1200.
IBN-Service Posts: 8946 Rating: (996)
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6/10/2012 11:42 AM	Rate (0)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 9/21/2023 Posts: 1499 Rating: (220)	IBN-Service Ganes10 schrieb: ...Yeah memory slice is a little bit different for S7-300 and S7-400 in STEP 7 v11. For example, can't we access a Double Word of DB1.DBD0 as DB1.DBX0.0 (as a Bool) or DB1.DBB0 (as a Byte) or DB1.DBW0 (as a Word) ?? Yes, you can, but unfortunately not symbolic but onlyabsolute. Or via P## operator and AR handling, what is not sovery nice / easy as the slice function of S7-1200. Hello IBN-Service, "Symbolic" here you mean is the way of accessing DB (S7-300/400) similar to slice memory concept in S7-1200, without remembering it's absolute address is it? What is the P## operator and AR handling? any info on that?
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