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HELP!!!!!Tell me how to calculate log.

Created by: AnproScott at: 1/25/2008 9:35 AM (7 Replies)

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1/25/2008 9:35 AM	Rate (0)
AnproScott Advanced Member Joined: 5/31/2007 Last visit: 9/23/2025 Posts: 90 Rating: (2)	We have theLN and EXP Math instructions in S7 Manager. I want to calculate the "log" Math ,and I do not find any relative instruction. Can anybody help me that how to do the log calculation?? Please give me the example code!..................... Thank you so much. by SexDriver

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1/25/2008 4:31 PM	Rate (0)
jacek d Platinum Expert Joined: 9/23/2005 Last visit: 12/23/2025 Posts: 5149 Rating: (772)	First - I won't comment your request... Second - hint 1 - there's no other log instruction in Step7 (but you could have a look at S5-S7 converting lib - some interesting FCs are there) hint 2 - google for "logarithm" or use wikipedia.
	Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
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1/28/2008 8:47 AM	Rate (0)
Aret Posts: 2348 Rating: (265)	Well, generally there is 1 rule: lg_a(b) = lg_c(b)/lg_c(a) you can use almost any positive numbers instead a,b,c (excluding 0 and 1)
Aret Posts: 2348 Rating: (265)	Last edited by: Aret at: 28.01.2008 08:49
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1/30/2008 9:02 AM	Rate (0)
jacek d Platinum Expert Joined: 9/23/2005 Last visit: 12/23/2025 Posts: 5149 Rating: (772)	Aret Well, generally there is 1 rule: lg_a(b) = lg_c(b)/lg_c(a) you can use almost any positive numbers instead a,b,c (excluding 0 and 1) For sure b CAN be equal to 1.
	Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
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1/31/2008 12:18 PM	Rate (0)
wolpi@ts Silver Member Joined: 3/6/2006 Last visit: 10/20/2025 Posts: 369 Rating: (101)	You need a result like shown in the hardcopy of the scl-state-screen? The SCL-Code for the LOG-function is res := LOG (in) The SCL-Code for the LN-function is res := LN (in) AWL-Code, generated by SCL-Compiler in the next issue Thomas Attachment Log_Ln_SCL.GIF (1377 Downloads)

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1/31/2008 12:22 PM	Rate (0)
wolpi@ts Silver Member Joined: 3/6/2006 Last visit: 10/20/2025 Posts: 369 Rating: (101)	This is S7-code, generated by SCL-Compiler from the LOG-command. The results are shown in the item above. Attachment Log_AWL.GIF (1150 Downloads)

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1/31/2008 12:23 PM	Rate (0)
wolpi@ts Silver Member Joined: 3/6/2006 Last visit: 10/20/2025 Posts: 369 Rating: (101)	And this is the code for ln-command Attachment Ln_AWL.GIF (987 Downloads)

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This contribution was helpful to 1 thankful Users AutoGen_7370286

5/16/2024 1:41 PM	Rate (2)
Rafa_Reis Member Joined: 2/17/2020 Last visit: 2/26/2025 Posts: 1 Rating: (2)	To calculate the LOG in Tia Portal, you can do it as follows: LOG(X) = LN(X)/LN(10)

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This contribution was helpful to 1 thankful Users Vincent!

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