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transient
Member

Join Date: Nov 2013
Posts: 5

Profibus Related Issue Need Urgent Help

11/16/2013 4:30 AM

Guys can you help me , i have three profibus RS 485 cables coming from System A , B , C and i have to connect them to my DCS controller , which has Profibus RS 485 slot , but only one .

Three Profibus cables are namely A with core 1,2

B with core 3,4

C with core 5,6

Now how to network these 3 cables and connect into one slot .

I have one option , as to connect 2,3 and 4, 5 and thus i will left with 1 and 6 .

Thus in this case i can connect 1,6 to Controller slot .

But then if then cable B damages , then will the whole system will go unhealthy?

Is there any other way , by the way i have an unused RS 232 and ethernet slot in controller interface. will that be if any help .

I need some advise .

Regards

Transient
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zohaib
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Join Date: Aug 2010
Posts: 2
#1

Re: Profibus related issue need urgent help

11/16/2013 4:59 AM

I think you can connect the devices in parallel rather than in series. All you need is the terminating resistors at all the devices.
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transient
Member

Join Date: Nov 2013
Posts: 5
#2
In reply to #1

Re: Profibus related issue need urgent help

11/16/2013 5:02 AM

ok Mr Zohaib , i will do that , but finally , how will i connect them to the controller bcz at controller i have only one Profibus (RS 485 port).
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zohaib
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Join Date: Aug 2010
Posts: 2
#3
In reply to #2

Re: Profibus related issue need urgent help

11/16/2013 5:19 AM

After connection in parallel you got a single pair of cable to connect at the controller end.
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transient
Member

Join Date: Nov 2013
Posts: 5
#4
In reply to #3

Re: Profibus related issue need urgent help

11/16/2013 10:55 AM

are you serious , i dont think u make sense here
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
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#5

Re: Profibus Related Issue Need Urgent Help

11/16/2013 11:36 AM

There are many sites on the internet dealing with the technicalities of Profibus. Those, plus the instruction manual sheets supplied with the equipment, will reveal everything that is needed.

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Iris
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Join Date: Jul 2010
Posts: 669
Good Answers: 176
#6

Re: Profibus Related Issue Need Urgent Help

11/16/2013 12:11 PM

If you truly have RS-485 lines, then you have Profibus DP. (Profibus PA is NOT RS-485)

Profibus DP over RS-485 wires from device to device to device to device, essentially parallel wiring.

In the diagram below, the green device is the master at address 1, the others are slaves at addresses 8, 5, 43, and 117. The grey line is a representation of the binary data, the purple line is a representation of the cabling from device to device to device.

The master happens to be in the middle, but it could be at either end.

"Termination" is done only at the physical ends of the network and is critical for proper network performance. The statement that "all devices are terminated" is not true.

You should consider consulting the Profibus.org site for well illustrated, comprehensive installation and commissioning manuals.
http://www.profibus.com/download/installation-guide/
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Iris (1); PWSlack (1); transient (2); zohaib (2)

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