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Same FB, different memory in S7-300 vs S7-1500

Created by: BiLaH at: 12/17/2014 10:50 AM (6 Replies)

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12/17/2014 10:50 AM	Rate (0)
BiLaH Advanced Member Joined: 10/14/2009 Last visit: 10/2/2024 Posts: 28 Rating: (0)	Hi everyone, I'm working with TIA Portal V13. When I use the same FB (same SCL code) in a S7-1500 and in a S7-300 the size of the FB and of the instance DB are different in terms of memory. Why? How can I estimate the size of a DB when I am creating it? Regards, Attachment MemoriaValvula.jpg (543 Downloads)
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12/18/2014 6:04 PM	Rate (0)
AutoGen_405229 Experienced Member Joined: 2/18/2013 Last visit: 3/12/2024 Posts: 102 Rating: (23)	You didn't provide enough information about your blocks, however you may find some answers and optionsin chapter 2.6 Optimized blocks in the following document: http://support.automation.siemens.com/WW/view/en/90885040

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This contribution was helpful to 2 thankful Users BiLaH William_B

12/18/2014 10:59 PM	Rate (0)
William_B Posts: 5225 Rating: (1195)	..also note that the new processors (S7-1200 and S7-1500) now also save the code documentation such as symbol names with descriptions as well as network titles. This reflex in the code's memory usage and not listed in a different category (as with other brands). You do not have a choise NOT to save documentation with the PLC (S7-1200 == fact, S7-1500 == guess). Try for yourself.. reduce the text used for documentation and see if the memory usage becomes less in the S7-1500. Cheers. w
William_B Posts: 5225 Rating: (1195)
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This contribution was helpful to 1 thankful Users BiLaH

12/19/2014 8:33 AM	Rate (0)
AutoGen_405229 Experienced Member Joined: 2/18/2013 Last visit: 3/12/2024 Posts: 102 Rating: (23)	William B. ..also note that the new processors (S7-1200 and S7-1500) now also save the code documentation such as symbol names with descriptions as well as network titles. This reflex in the code's memory usage and not listed in a different category (as with other brands). You do not have a choise NOT to save documentation with the PLC (S7-1200 == fact, S7-1500 == guess). Try for yourself.. reduce the text used for documentation and see if the memory usage becomes less in the S7-1500. Cheers. w Right, the 1200 and the 1500 are identical regarding code and data documentation. In detail, the documentationis part of the load memory size of a code or data block. For code blocks (OB, FB, FC) the purecode sizeis reflected in thework memory size. For data blocks the work memory size reflects the pure data size. If the load memory sizeof blocks is thebottleneck, you could use a memory card with more capacity. If the code work memory size is the bottleneck, you may optimize your code or use a PLC type with more work memory. If the data work memory size is the bottleneck, you mayoptimizeyourdata or use a PLC type with more work memory. In some special cases it may be possible to have some DBsin load memory only.

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This contribution was helpful to 2 thankful Users BiLaH William_B

12/19/2014 9:23 AM	Rate (0)
BiLaH Advanced Member Joined: 10/14/2009 Last visit: 10/2/2024 Posts: 28 Rating: (0)	Thank you everybody! Please, find attached another file. As you can see, I have a TIA Portal project with 3 different CPU: IM151-8, S7-300 and S7-1500. I created a simple FB (in this case in KOP) with two inputs and one output. I used this FB in the IM151 and in the S7-1500 with his instance DB. I compiled both CPUs and I looked at their properties. What I found is that I need 16 times more load memorie and 4 times more work memorie in the S7-1500 than in the IM151-8. Note that the S7-300 works like the IM151, so I had not included it in the attached file. Regards, Attachment TEST.jpg (620 Downloads)
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12/19/2014 10:42 AM	Rate (0)
Usab Posts: 33 Rating: (4)	Hello , Different CPU has different compile factors. So it is normal to have different size when you compile the same block on different CPUs. Sometimes it even differs between firmware versions for the same CPU. Usab
Usab Posts: 33 Rating: (4)
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12/19/2014 10:45 AM	Rate (0)
AutoGen_405229 Experienced Member Joined: 2/18/2013 Last visit: 3/12/2024 Posts: 102 Rating: (23)	BiLaH Thank you everybody! Please, find attached another file. As you can see, I have a TIA Portal project with 3 different CPU: IM151-8, S7-300 and S7-1500. I created a simple FB (in this case in KOP) with two inputs and one output. I used this FB in the IM151 and in the S7-1500 with his instance DB. I compiled both CPUs and I looked at their properties. What I found is that I need 16 times more load memorie and 4 times more work memorie in the S7-1500 than in the IM151-8. Note that the S7-300 works like the IM151, so I had not included it in the attached file. Regards, For your example yourfinding "need 16 times more load memory and 4 times more work memory in the S7-1500 than in the IM151-8" is right, however this is not a general rule. In the 1500even emptyblocks use some work memory. If you want to make a more general rule you would need to separate between this basic consumption and the consumption for code or data. Dependent on the code or the data definition and dependent on the prioperties (optimized or standard)the additional consumption compared to the IM151-8 may be better or worse. For data there may be up tofactor 8 in case you work only or almost only with Bool variables in optimized mode. If you work with standard mode data should have the same memory consumption like in IM151-8.

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