How to check actual memory consumption with Siemens S7 software

kemppioy

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• Oct 27, 2005

• #1

Hello,

I am very very new with Siemens S7 and I was wondering how to check the actual memory consumption of the S7 cpu while offline? How do I open the project and then check how much memory is used? Thanks for your help!

PK

 

marius

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• Oct 27, 2005

• #2

... in step7 you can see memory consupmtion of particular blocks, if you will select all of them (ctrl+a), on the bottom bar ... approximate size is showed (it works in both branches - Sources & Blocks) ... maybe it is too possible to check more precisely by using simulator and then try it like in online mode ... PLC -> Diagnostic/ Settings -> Module Information -> Memory

 

Anie

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• Oct 27, 2005

• #3

Hi there,
To see the memory consumption just open your S7 project then go to the menu PLC>Diagnostic/setting>Module Information ..., In module information(Memory Tab) you can see the allocated memory and also work memory of your CPU. But you have to do it online while connected to your PLC. I hope that answer you question.

 

ivo.maenen

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• Oct 27, 2005

• #4

In the 'Simatic Manager' you must select the map 'Blocks'. Click with the 'righside-button' of the mouse on 'Blocks'. You will see a new menu. In this menu you must select the page 'Blocks'. There you will find the amount of load- and workmemory of your program.

 

JesperMP

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• Oct 27, 2005

• #5

If you try to estimate the consumed memory offline (without looking at the module information online), then it is not enough to just add the blocks together.
In addition to the blocks there is memory set aside to the system settings and communication connections. Especially the communication connections can take up a surprising amount of memory.

Try to compare the size of the the blocks offline and what work mem is used online. You will notice a significant difference.

 

kemppioy

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• Oct 27, 2005

• #6

So basically what everyone is saying is that I need to go online to get an idea of the exact memory usage? Problem is that the current processor we are using is not sold anymore so we are checking to see the processor that we should order based on the memory consumption of the plc program that was used with the old cpu. I didn't make the plc program so we are not sure of its memory usage.

Thanks
PK

 

Amr Hassan

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• Oct 27, 2005

• #7

u can do that by the comparison of the data sheets of both cpu .

 

kemppioy

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• Oct 27, 2005

• #8

I can check the data sheets but that doesnt tell me the usage of the plc program itself.

 

Amr Hassan

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• Oct 27, 2005

• #9

yes but u can estimate how big is the old program and what is the nearest cpu u can use

 

marius

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• Oct 27, 2005

• #10

JesperMP said:

If you try to estimate the consumed memory offline (without looking at the module information online), then it is not enough to just add the blocks together.
In addition to the blocks there is memory set aside to the system settings and communication connections. Especially the communication connections can take up a surprising amount of memory.

Try to compare the size of the the blocks offline and what work mem is used online. You will notice a significant difference.

Click to expand...

in the most-top branch of project ... 'Other Stations' and 'MPI' have visible size ... is this what you mean? in my case ... about 4kb together

 

JesperMP

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• Oct 27, 2005

• #11

in the most-top branch of project ... 'Other Stations' and 'MPI' have visible size ... is this what you mean? in my case ... about 4kb together

Click to expand...

Offline: In the project tree, go to blocks and open the properties. Select the "Blocks" tab and you can see the Total "Size in work memory".

Online: Open the "Module information" for the CPU and select the "memory" tab. Observe the "Wok memory" column at the "Total" row.

There will be a difference between the offline and the online values.

 

ivo.maenen

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• Nov 11, 2005

• #12

Info from Siemens

I found this on the Siemens website. It's explains why there is a difference, the effect of START-UP and how you can calculate the extra memory.