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profiBUS topology

Created by: trialghost at: 8/4/2009 1:27 PM (10 Replies)

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8/4/2009 1:27 PM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	Hi every one i have 2 Question 1- Can i detect my profibus network topology i mean "cable lenth" among the network. is that can be done using PG and diag. reapeter 2- What is the max cable lenth between 2 nodes because i have a random communication problem and it may because of cabele lenth. _{i already have a cable 90m and i don't know is that permissable}

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8/4/2009 3:12 PM	Rate (2)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 11/11/2024 Posts: 12293 Rating: (2691)	Hello trialghost; Let's see if we can provide you with some answers: 1- Can i detect my profibus network topology i mean "cable lenth" among the network. is that can be done using PG and diag. reapeter Here is what the Diagnostic Repeater for Profibus-DP explains the functionnalities of the repeater: *2.2 Topology data: bus topology and topology table* The diagnostic repeater supplies data on the bus topology that consist of PROFIBUS addresses of the nodes and of relative distances of the nodes to the diagnostic repeater. The data on the bus topology can be read out by STEP 7, displayed graphically or in tabular form, printed out, and exported as a CSV file. It is also possible in the user program to read out the topology data from the diagnostic repeater as records and format them for visualization. 2- What is the max cable lenth between 2 nodes because i have a random communication problem and it may because of cabele lenth. _{i already have a cable 90m and i don't know is that permissable} The maximum length of a Profibus segment will depend on the speed selected for the network bus. Have a look at the following attachment, extracted from an old Siemens presentation (the data is still valid, no worry). Hope this helps, Daniel Chartier Attachment PB_Distance.jpg (583 Downloads)

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8/8/2009 1:45 PM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	dear: Daniel Chartier very thanks for your co-operation you said The data on the bus topology can be read out by STEP 7, displayed graphically or in tabular form, printed out, and exported as a CSV file. It is also possible in the user program to read out the topology data from the diagnostic repeater as records and format them for visualization. can you pls explain how.

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8/9/2009 9:33 AM	Rate (2)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 11/11/2024 Posts: 12293 Rating: (2691)	Hello trialghost; As you seem to be new here, I will explain how you can locate the information yourself. When a manual is suggested, please start by opening it. If you do not have it with you, you can locatein the Product Support link that you will find at the top of this page. Use the search box, and you can refine the search by clicking on Manuals, FAQs, Downloads.... For instance, here is a link to the Diagnostic Repeater manual that I suggested earlier: http://support.automation.siemens.com/WW/view/en/7915183 Chapter 7.4 is dedicated to accessing the topology of your bus: Procedure [Bus topology] 1. In STEP 7 select the DP master system whose data you want to read. 2. Start the function by choosing the menu command View > Display > All Stations/Only Diagnostic Repeater with Stations/All Diagnostic Repeaters Only. Procedure [Topology table] 1. In the topology display, select the diagnostic repeater whose data you want to read. 2. Start the function by choosing the View > Topology table menu command. Procedure [Diagnostic Buffer info on the Reapeater] 1. In the topology display, select the diagnostic repeater whose data you want to read. 2. Start the function by choosing the Options > Diagnostic buffer menu command. Hope this helps, Daniel Chartier

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8/10/2009 5:40 AM	Rate (1)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 11/11/2024 Posts: 3026 Rating: (1057)	trialghost It is also possible in the user program to read out the topology data from the diagnostic repeater as records and format them for visualization. Yes it is and and just in case you have not located this yourself already,chapter 7.3 of the manual is dedicated to this. You can also trigger a topology detection from your S7program via SFC103 "DP_TOPOL". And onelast thing: Please make sure to adhere tothe design guidelines and be aware of the limitations (see chapter 3 of the manual for more)to ensure you get the results that you needfrom the Diag repeater.
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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8/11/2009 9:37 AM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	thanks every body i read the manual and i could mange the connection with the diag. R and i would like to inform you this =>when i started the measurment it stooped due to error (SF led) and it recommended me to add. DR in between and i will in the next stop of the production line => i need to adjust the repeater time but when i open SFC1 READ_CLK i found it empty, all SFCs are blank. can any one explain why. and how to fix it?

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8/11/2009 9:59 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 11/11/2024 Posts: 3026 Rating: (1057)	trialghost => i need to adjust the repeater time but when i open SFC1 READ_CLK i found it empty, all SFCs are blank. can any one explain why. and how to fix it? SFC's (or SFB's for that matter) are part of your S7 CPU's Operating system and as suchalready "exist" in you CPU (you can not - nor need to - download them). The "System Function Blocks" library in Step7 "merely" contains them so you can callwhichever one you need inyour S7 logic(the library really just provides you with a call interface for them, they are nonethess additonally marked as Know How protected). Bottom line, don't worry that they appear to be empty, they'll work as outlined in their associated help (highlight SFC1 in the library or your project and hit <F1> to get to the inbuilt help for it). Ihope this helps
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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8/14/2009 1:51 PM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	dear fritz i tried to understand your message " about SFC1" but i couldn't "my fault because i'm just beginner in that matter" any way we can jump this matter for now i need your help in the following i building the network from the begining and i wanna do it as standerd please take a look to the attached and tell me which config is better "long cable then repeater then nodes OR long cable then nodes then repeater " i search the manual for an answer but i fail. waiting to hear from you Attachment which config is better.GIF (484 Downloads)
	Last edited by: trialghost at: 8/14/2009 1:54 PM
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8/14/2009 3:29 PM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 11/11/2024 Posts: 3026 Rating: (1057)	trialghost dear fritz i tried to understand your message " about SFC1" but i couldn't"my fault because i'm just beginner in that matter" or it's because of an incrompehensible answer on my behalf trialghost i need your help in the following i building the network from the begining and i wanna do it as standerdplease take a look to the attached and tell me which config is better "long cable then repeater then nodes OR long cable then nodes then repeater " i search the manual for an answer but i fail. my answerdepends on what baudrate you want to run dear trialghost. Genereal stuff first: Make sure you only have a max of 100m per DP2/DP3 Segment of the Diag repeaterirrespective of the choosen baudrate (this is the max "monitoriable"/useful Segment lenght for a Diag repeater as you probably know already, if not seechapter 3.1.4 of the manual). If it is 1.5 Mbps: Fig 1 is "wasteful" in this case. You can start of from the CPU with up to 200meters (max. Segment lenght for 1.5 Mbps) before you connect to the DP1 port of the first repeater. This way you save yourself one Diag repeater (assuming you live without the ability to detect the distance of a cable break on this first segment). If it is >=3 Mbps: Both solutions will work equally well in my humble opinion (100meters is max permissible segment lenght now, irrespective if Diag or normal repeaters are used). I'd probably go for Fig 2 though, just because it seems logical to have at least some devices on a Diag repeater segment (and presumingthat you will have a bunch of more Slavesdownstream of the 2nd Diag repeater). Having said that, my advise is to stick with baudrates of <=1.5Mbps unless you have a jolly good reason to go faster. If you want to (have to) go"faster"I advise you to pay heed to chapter 3 of this manual(which is a good reference document to have in genereal): SIMATIC NET PROFIBUS Network Manual System Manual I hope this helps
	Last edited by: fritz at: 8/15/2009 2:26 AM Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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8/14/2009 8:01 PM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	fritz trialghost wrote: dear fritz i tried to understand your message " about SFC1" but i couldn't"my fault because i'm just beginner in that matter" or it's because of an incrompehensible answer on my behalf I hope this helps i think you are right you are indeed incrompehensible can you please answer the Q in simple way , and give me the pdf manual link "the refrence for your answer because it will be simple with respect to yours" any way the baudrate 500kbps and the length of cables not exact i just wonder witch is more resonableand why
	Last edited by: trialghost at: 8/14/2009 8:05 PM
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