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Spur line

Created by: Adi_EA ID at: 11/16/2009 3:40 PM (7 Replies)

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11/16/2009 3:40 PM	Rate (0)
Adi_EA ID Posts: 7 Rating: (0)	Dear All, I have a confusing in descibe spur line (profibus application). Please advice what is spur line? what is correlation spur line with weighting value? I find such statement "the sum of their weighting values does not exceed the value 5" please also advice in more detail regarding above statement. thanks very much for your reply regards adi
Adi_EA ID Posts: 7 Rating: (0)
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11/24/2009 12:54 PM	Rate (0)
LesPaul Posts: 467 Rating: (59)	hello Adi_EA ID, without the source of the document we cannotgive an exact solution Pleare have a lookto the profibus manual, I think it will help you http://support.automation.siemens.com/WW/view/en/35222591 kind dregards
LesPaul Posts: 467 Rating: (59)
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This contribution was helpful to 1 thankful Users AutoGen_654104

11/24/2009 2:10 PM	Rate (0)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 3/16/2025 Posts: 12344 Rating: (2707)	Adi_EA ID Dear All, Please advice what is spur line? Ĥello Adi; A spurline refers to an extension from the main trunk; it is a wire that connects a bus element to the bus, using some form of T-junction. Profibus uses a daisy-chain bus topology, and limits the use of spurlines very strictly. In the PTO Profibus Installation Guide it is even recommended to never use them.In the PIC cabling guide, it is stated that spurs should not be used at speeds above 1,5 MB (they add capacitance to the lines) but that at lower speeds the total length of all spurs on a bus should never exceed a maximum of 6 m. Using these numbers we used Weidmuller T-junctions on our Profibus-DP lines to connect to slaves in our projectsthat came without standard Profibus sub-D 9-pin connections (valves, flowmeters, instruments...); we kept all spurlines at less than 20 cm eachto ensure good communications at 1,5 kB. what is correlation spur line with weighting value? As Les explained earlier, the "weighting value" is not a standard Profibus term, and unless we have access to the original document you are refering to it will be quite difficult to help you out on this issue. Hope this helps, Daniel Chartier
	Last edited by: dchartier at: 11/24/2009 2:10 PM
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11/25/2009 4:44 AM	Rate (0)
Adi_EA ID Posts: 7 Rating: (0)	Halo Les, I also refering to the same document. Please see page 45 (table 3-5). halo daniel, thanks for your explanation. Please also advice based on the attached "example profibus connection.pdf".Canwedefinesuch connection as spur line also? for weighting value, i refer to the same document as Les refer. regards adi Attachment example profibus connection.pdf (771 Downloads)
Adi_EA ID Posts: 7 Rating: (0)
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11/25/2009 6:40 PM	Rate (0)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 3/16/2025 Posts: 12344 Rating: (2707)	Hello Adi; Yourdrawing does represent a connection through a spurline. However, since the Simocode units come with an integrated sub-D connector for the Profibus connection, I wonder why you should need one; the connection should be daisy-chained, using a certified Profibus connector. Remember that any connection on the bus will add a capacitive value that could disturb communications, especially at high speed. The Profibus connectors have integrated impedance-balancing circuits that help reduce the effect of capacitive loading, and all Profibus network designers should use them as soon as integrated connections are available. The term "weighting factor" is a new one for me. The older version of the Profibus manual used "value factor" instead, which probablycomes out to the same,most likelyfrom a German-to-English translation. They do give you guidelines to do your calculations for high-speed Profibus networks, however they do not address the problem of spurlines (except those for PG connections), since they assume that at 1,5 MB and above youshould not use them. Hope this helps, Daniel Chartier

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11/26/2009 5:44 AM	Rate (0)
Adi_EA ID Posts: 7 Rating: (0)	Hello Daniel, Much appreciated your explanation. We do this spur line connection cause we install the simocode inside a bucket (withdrawable unit). That is the reason we added terminal as a junction. I am thinking to change the terminal (X19 for e.g) with some T-juntion which has integrated impedance-balancing circuits (same as profibus connector). Do you have any idea, where i can find such T-junction? thanks & regards adi
Adi_EA ID Posts: 7 Rating: (0)
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11/26/2009 6:21 AM	Rate (0)
fritz Diamond Member Joined: 10/7/2005 Last visit: 3/17/2025 Posts: 3042 Rating: (1061)	Hello Adi_EA ID it seems you really will have to deliberately create spurlines and as Daniel already said, they are ideally avoided all together in a Profibus installation (and quite rightly so as far as I'm concerned). As such I wonder if usage of the so called ProfiHub from Procentec is worth your while considering for your application. AProfiHub is - in simple terms -nothing else but a bunch of 5 repeaters put intoone package. It has been around for some years,I've personally used it numerous times andit works like a treat(Disclaimer: The company I work for are distributors for Procentec gear, just to get the "conflict of interest" notice out with this advise). You'd use it in your case to have one device (e.g. Simocode) connectedper channel and elimate all your spurlines problems (every channel is fully "repeated' and can have up to 31 devices connected to it. While yourinstalltion may look like it has plenty of spurlines, it has in fact none). Anyway, food for thought and I hope it 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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11/26/2009 1:22 PM	Rate (0)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 3/16/2025 Posts: 12344 Rating: (2707)	Hello Adi; Fritz' suggestion of the Profihub is one we have looked at in our projects, it is a certified solution and a very good one. We finally decided to use Weimuller T-connectors, as mentionned earlier; the part number is 8714260000 for a standard T-connector, and 8714240000 for a T-connector end-of-line with integrated terminator. I am attaching a diagram that will show the design of the unit. You will find similar units in the offerings of Turck and Phoenix Contacts, to my knowledge. Other manufacturers may offer variations on the subject. Hope this helps, Daniel Chartier Attachment T-CONN_rev.jpg (609 Downloads)

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