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v and m memory

10/7/2011 8:26 AM	Rate (0)
saeedplc Posts: 288 Rating: (4)	hello. what is difference between v and m memory? can i use v memory instead of m memory and vice versa? best regards.
saeedplc Posts: 288 Rating: (4)
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10/7/2011 8:40 AM	Rate (0)
Wizard Diamond Member Joined: 4/24/2006 Last visit: 9/15/2025 Posts: 9027 Rating: (1199)	Hello saeedplc, The V-memory is the memory in Datablock. The M-memory is internal memory bits. You can use them both. The first 112 M-Memory bits are stored in EEPROM by power down. The V-memory you can assign an initial value. Best regards, Wizard

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10/7/2011 9:14 AM	Rate (0)
saeedplc Posts: 288 Rating: (4)	thank you for the reply. best regards.
saeedplc Posts: 288 Rating: (4)
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10/21/2011 5:57 PM	Rate (0)
William_B Posts: 5225 Rating: (1204)	I am going to drop a cautionary tip in there.. Take care.. if you select to download the "datablock" it will wipe out any information written in V memory. In our case we have cutomer settings saved there -- so if we download a program we make sure not to download the datablock too. Something else.. V-memory is what datablocks use to store information for things like the positioning wizard. Luckily when you do a datablock download "datablocks" these information is restored to its original state. Make sure not to use V-memory that clashes with what the datablocks use. Also.. It is recommendable to use the S7-200's memory cartrages to store important user data like a machine setup. This can be done using recipes. However.. not all PLCs and not all memory cartrages work. -- if you wish to know more.. start a new thread about how the recipe concept works.
William_B Posts: 5225 Rating: (1204)
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10/26/2011 6:37 PM	Rate (0)
namnguyen Posts: 3 Rating: (0)	Hi V is ROM memory M is RAM memory
namnguyen Posts: 3 Rating: (0)
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10/26/2011 7:00 PM	Rate (0)
William_B Posts: 5225 Rating: (1204)	namnguyen Hi V is ROM memory M is RAM memory Hi there! Sorry for saying..are you asking or are you saying? ROM = Read Only Memory V-memory can be changed; it is also volitile if no copy is made in the EEPROM. M-memory is not always volitile, it depends on how the system block is set for retentive ranges. Greetings. W
William_B Posts: 5225 Rating: (1204)
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11/1/2011 11:52 AM	Rate (0)
Maverick_Adani Posts: 3 Rating: (0)	Dear Saeed V stands for volatile memory which means its value can be changed suddenly if they are not defined in the retentive region.it is always advisable to use memory bits(M) when you are defining or transferingimportant datas as they are stored in the memory itself so it can be retended. V memory you can use in HMI tag bits for alarms,warnings and receipes and other things,because you are having limited memory bits so you need to keep them spare and not to use in normal config..Also it is advisable to not useM bits all the time rather you can go withV area in normal usage.... Regards Maverick
Maverick_Adani Posts: 3 Rating: (0)
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11/15/2011 2:03 PM	Rate (0)
moose Experienced Member Joined: 1/12/2011 Last visit: 8/28/2025 Posts: 65 Rating: (5)	V Memory is the best, approx 5000 bytes free, M memory I never use. Never have to write in datablock.

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