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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: 12/29/2020 Posts: 167 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 Grandmaster-Expert Joined: 9/27/2006 Last visit: 3/2/2021 Posts: 10452 Rating: (2212)	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: 12/29/2020 Posts: 167 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: 3/1/2021 Posts: 182 Rating: (4)	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 Posts: 1064 Rating: (71)	It should have no effect at all except to free up memory (fill in memory holes from edits)
playerslight Posts: 1064 Rating: (71)
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6/21/2013 9:11 AM	Rate (0)
Hit_Formula Experienced Member Joined: 2/20/2010 Last visit: 2/19/2021 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 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: 11/19/2020 Posts: 725 Rating: (70)	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 (286 Downloads)

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6/25/2013 4:40 AM	Rate (0)
Saravana kumar Gold Member Joined: 2/6/2009 Last visit: 11/19/2020 Posts: 917 Rating: (113)	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: 2/11/2021 Posts: 701 Rating: (28)	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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