5/13/2013 6:55 AM | |
Posts: 112 Rating: (2) |
DEAR ALL, i have an system of 315 plc and ( slave devices of 22 numbers) 10 sinamics G120 240E-2DP drive and PEPPERL+FUCHS( Absolute Rotary Encoder )10 numbers and DP/PA coupler and LR 400 LEVEL SENSORS, through PA network AND THE DISTANCE IS ALSO QUIT LONG AND COMMUNICATION (baud rate 93.75kbps) For communicating with the slave devises i am using an profibus repeater and the connection configuration is in the download file THE PROBLEM IS, 1, FOR THE DESIGNED NETWORK I HAVE NO PROBLEM IN COMMUNICATION FOR 1 MONTH but now communication problem arises . 2, BUT now the communication is healthy for only for 7 encoder and the dp/pa network and 2 level sensors, 3, I am not able to communicate with the drive and remaining 3 encoder and drives. but if i remove the encoder network i can able to get communication with only 3 drives but terminations are proper 4 I have to know weather the communication network what is shown is fine according to the standard or it against the standard of design to get communication. PLEASE PROVIDE ME PROPER SOLUTION AND GUIDANCE TO SOLVE THE COMMUNICATION PROBLEM ..................... Attachmentprofibus COMMUNICATION_anbu.PDF (386 Downloads) |
5/13/2013 11:13 AM | |
Joined: 10/7/2005 Last visit: 4/20/2024 Posts: 3004 Rating: (1046)
|
Hello GOWDA not to sure how to say this politely, but your Network Topology is a bit of a mess and in parts NOT in accordance with the Profibus Standards. The main issue is the usage of what you call "Junction 1" and "Junction 2". If these are indeed simple junction boxes you are creating so called spurlines (aka stublines or branch lines) on your DP network. Spurlines are arguably best avoided all together in a DP Network (personally, I would avoid them like the plague). The Profibus standard does though allow for a certain amount/lenght of them in a DP Segment (unfortunately in my opinion). In your case (93.75kbps), the standard allows for a total Spurline lenght of 100m per segment or a maximum Spurline Capacity of 3nF per segment (whichever comes first, assuming you use Profibus cable type A, the max Spurline Capacitywill be reached atthe max Spurline lenght). While your design may fullfil this (please check this), you have broken the terminating rule for a few Segments. Put simple, each DP Segment must be terminated at the start and at the end. Spurlines are however branches of the Segment and must NOT be terminated (and ideally avoided all together, but I think I mentioned that one already ) so some of your Segments currently suffer from "over termination". My advise: 1.) Go to www.profibus.com, download and study the free of charge available Design and installation guidelines . 2.) Therafter, redesign your network and remove all spurlines from it (add more repeaters if need be or consider using Procentec's Profihub or - even better - COMbricks). 3.) Get yourself Procentec's Profitrace 2 based toolkit to do a thourough study of your DP and PA Network once done (to ensure all is indeed in order and you don't have other installation related issues to deal with). I hope this helps and for the record, I do have an affiliation with Procentec. |
Cheers |
|
5/16/2013 8:05 AM | |
Posts: 112 Rating: (2) |
DEAR SIR I have gone through your answers thanks for replay .............. but what step i can take weather i ave re arrange the network or using some (external profibus repeater ) will give efective for communication......... |
5/20/2013 2:35 AM | |
Joined: 10/7/2005 Last visit: 4/20/2024 Posts: 3004 Rating: (1046)
|
Hello GOWDA it'll certainly eliminate the spurlines in your design and is as such highly recommended. Providing your installation is in general in compliance with the Profibus Installation guidelines and you don't have any fault devices, itshould also solve your problem. Question is: Have you downloaded andread the free of charge available Profibusguidelines from www.profibus.com and checked if your installation complies? P.S: The cascading depth of 9 repeaters applies to Siemens repeaters, Procentec repaeters (e.g. B1, ProfiHub's) have an unlimited cascading depth, just to mention it. I hope this helps |
Cheers |
|
Follow us on