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work memory

Created by: a.z.r at: 6/16/2013 11:59 AM (30 Replies)

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6/16/2013 11:59 AM	Rate (0)
a.z.r Bronze Member Joined: 6/8/2013 Last visit: 11/11/2019 Posts: 161 Rating: (0)	hi all we have a plc s7-400 in my factory that programmed for boiler project..but in options in HW.CONFIG workmemory is 93%...is this dangerous? please explain for me...admissible amount for workmemory ? please help me

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6/16/2013 2:06 PM	Rate (0)
dchartier Diamond Expert Joined: 9/27/2006 Last visit: 11/15/2019 Posts: 8749 Rating: (1802)	Hello azr; Work memory usage at 93% is high, but not "dangerous", in the sense that it will not cause a crash of the CPU or make it go to STOP mode. However, if you plan to modify the program and add new functions, you might find that you could not be able to download the new blocks, because of memory shortage.. See if the "Compress" button (in the same page as shows the actual % of memory use, in CPU properties) can bring the level of Work memory use down a bit, if you wish. Hope this helps, Daniel Chartier

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6/18/2013 9:40 PM	Rate (0)
a.z.r Bronze Member Joined: 6/8/2013 Last visit: 11/11/2019 Posts: 161 Rating: (0)	hi,,,,thank u of your help

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6/20/2013 12:41 PM	Rate (0)
ashishm Bronze Member Joined: 2/1/2011 Last visit: 10/28/2019 Posts: 182 Rating: (3)	Dear Sir, If we try to compress the memory in PLC than will it effect the time stamping of IO in plc. will it effect in scan cycle or any other effetc. will it be normal to compress memory

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6/20/2013 12:43 PM	Rate (0)
playerslight Platinum Member Joined: 4/30/2008 Last visit: 10/2/2017 Posts: 1064 Rating: (71)	It should have no effect at all except to free up memory (fill in memory holes from edits)
	Regards Steve Don't worry about walking a mile in my shoes Just try think for a day in my head
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6/21/2013 9:11 AM	Rate (0)
Hit_Formula Experienced Member Joined: 2/20/2010 Last visit: 9/24/2019 Posts: 104 Rating: (7)	Work Memory can be reduce after modification in standard Function block, other way use STL or SCL langauge in program which help you to reduce work memory

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6/24/2013 5:20 PM	Rate (0)
cjustice Member Joined: 2/21/2013 Last visit: 8/27/2013 Posts: 1 Rating: (0)	You can also take a look at your diagnostic buffer size and process image size. You can gain a large amount of room here. You process image area for the input and outputonly really needs to be as large as your max I/O address, and you can shrink the number of diagnostic messages down as small as you like. These are on the cycle/clock memory and diagnostics/clock tab for the CPU in hardware manager.

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6/24/2013 6:44 PM	Rate (0)
manmeet Gold Member Joined: 1/3/2006 Last visit: 11/6/2019 Posts: 725 Rating: (63)	Hi Just to elaborate on whatcjustice said below is the excerpt from Step 7: The size of the work memory which can be used for logic blocks and data blocks can be altered by changing any of the following parameters: The size of the process image (byte-wise, in the "Cycle / Clock Memory" tab) Communication resources (S7-400 only, in the "Memory" tab) The size of the diagnostic buffer (in the "Diagnostics / Clock" tab) Number of local data for all priority classes (in the "Memory" tab) You can have a look at attached file for more fun. Attachment Work Memory.pdf (254 Downloads)

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6/25/2013 4:40 AM	Rate (0)
Saravana kumar Gold Member Joined: 2/6/2009 Last visit: 11/13/2019 Posts: 917 Rating: (112)	Hi, 93% work memory is not a problem at all. But if it happens for your to add some more logic into the PLC in future for additional requirement then it will become difficult task to reduce the work memory and PLC won't allow you to download if it exceeds its limit. It will become difficult to STOP the PLC when the plant is running. So it safer to plan enough free Work Memory at this stage itself. The Major part of Work Memory can be reduced using the Unlink DBfor the user Data blocks. Unlink DB makes the Data blocks to get downloaed only into the Load Memory. Whenever required it can be copied into the Workmemory via SFB;s. Please check the following thread for more information and sample project about Unlink DB. https://www.automation.siemens.com/tf/WW/en/Posts/45535
	Last edited by: Saravana kumar at: 6/25/2013 4:46 AM Last edited by: Saravana kumar at: 6/25/2013 4:45 AM _______________________________________________________________ Best Regards T.Saravana Kumar "All for the Best"
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6/25/2013 7:42 AM	Rate (0)
vipz Gold Member Joined: 9/2/2012 Last visit: 11/13/2019 Posts: 681 Rating: (24)	Dearcjustice, can you please eleborate You process image area for the input and outputonly really needs to be as large as your max I/O address can you explain with some examples mentioning address range and corresponding process image size ?? regards Vipz
	With Best Regards VIPZ
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6/25/2013 8:49 AM	Rate (0)
Khaled_Ezzat Silver Member Joined: 9/7/2007 Last visit: 4/14/2019 Posts: 550 Rating: (61)	vipz Dearcjustice, can you please eleborate You process image area for the input and outputonly really needs to be as large as your max I/O address can you explain with some examples mentioning address range and corresponding process image size ?? regards Vipz Hi vipz If the process image area for example 512 then if you have an PIW 1024 as an analog input it will not be read by the CPU.
	Best Regards
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6/25/2013 9:02 AM	Rate (0)
vipz Gold Member Joined: 9/2/2012 Last visit: 11/13/2019 Posts: 681 Rating: (24)	Thanking you for quick reply.. what about piw514 onwards (for eg.) ?? Is there is any other cases we need to expand the process image area?? That is if cpu support to cahnge the process image size 1. cpu process image area = 256 i am using only 1 AI card, then address piw 520 (eg.) possible ?? or i need to use below piw 256 ?? regards vipz
	With Best Regards VIPZ
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6/25/2013 9:13 AM	Rate (0)
playerslight Platinum Member Joined: 4/30/2008 Last visit: 10/2/2017 Posts: 1064 Rating: (71)	the piw would have to be below 256 fo rit to be read
	Regards Steve Don't worry about walking a mile in my shoes Just try think for a day in my head
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6/25/2013 9:40 AM	Rate (1)
vipz Gold Member Joined: 9/2/2012 Last visit: 11/13/2019 Posts: 681 Rating: (24)	Dear playerslight, please find the attachment. screenshots are taken from uploaded backup from a running plc. adress used crossing the limit, but still its working ?? or its applicable for central rack only ?? regards vipz Attachment PROCES IMAGE.zip (60 Downloads)
	With Best Regards VIPZ
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6/25/2013 9:55 AM	Rate (1)
Saravana kumar Gold Member Joined: 2/6/2009 Last visit: 11/13/2019 Posts: 917 Rating: (112)	vipz Dear playerslight, please find the attachment. screenshots are taken from uploaded backup from a running plc. adress used crossing the limit, but still its working ?? or its applicable for central rack only ?? regards vipz Hi, There is no problem even if the actual IO used are more than the process image configured. Since you have Analog IO which are more than the process image area there is no need to change anything in the program. If you have any Digital IO's address more than the the process image area ( For Example DI 16 Channel address 600) then you cannot access the Inputs/Outputs directly into the program as I 600.0, I 600.2, etc . , You can access IO as PIW 600 only. You have to make a addtional programming to map the PIW 600 to the DB address or Memory address for using the inputs as bit.
	Last edited by: Saravana kumar at: 6/25/2013 10:00 AM _______________________________________________________________ Best Regards T.Saravana Kumar "All for the Best"
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This contribution was helpful to 2 thankful Users playerslight vipz

6/25/2013 10:12 AM	Rate (0)
playerslight Platinum Member Joined: 4/30/2008 Last visit: 10/2/2017 Posts: 1064 Rating: (71)	vipz Dear playerslight, please find the attachment. screenshots are taken from uploaded backup from a running plc. adress used crossing the limit, but still its working ?? or its applicable for central rack only ?? regards vipz soory i was mistaken in my last comment . After some further reading process image is i/o pii or piq (digital I believe) and the one that you have there is peripheral piw or pqw which are not included in the image table the help files in simatic manager explains it
	Last edited by: playerslight at: 6/25/2013 10:13 AM Regards Steve Don't worry about walking a mile in my shoes Just try think for a day in my head
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This contribution was helpful to 1 thankful Users vipz

6/25/2013 10:28 AM	Rate (0)
vipz Gold Member Joined: 9/2/2012 Last visit: 11/13/2019 Posts: 681 Rating: (24)	thank you all for the support.. regards vipz
	With Best Regards VIPZ
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6/25/2013 10:37 AM	Rate (0)
playerslight Platinum Member Joined: 4/30/2008 Last visit: 10/2/2017 Posts: 1064 Rating: (71)	You are welcome hope i helped
	Regards Steve Don't worry about walking a mile in my shoes Just try think for a day in my head
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6/25/2013 12:26 PM	Rate (0)
manmeet Gold Member Joined: 1/3/2006 Last visit: 11/6/2019 Posts: 725 Rating: (63)	You can access IO as PIW 600 only. You have to make a addtional programming to map the PIW 600 to the DB address or Memory address for using the inputs as bit. Hi Saravana, Here PIW600 is never read by PLC so mapping them onto bits is of no use. It won't update/read PIW 600 since its outside the range defined in CPU hardware configuration. Regards, Manmeet.
	Last edited by: manmeet at: 6/25/2013 12:26 PM
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6/25/2013 1:23 PM	Rate (0)
Saravana kumar Gold Member Joined: 2/6/2009 Last visit: 11/13/2019 Posts: 917 Rating: (112)	Hi, I have mensioned if PIW 600 is assigned to any of the IO card in the hardware configuration.
	_______________________________________________________________ Best Regards T.Saravana Kumar "All for the Best"
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