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Maximum Number of Profibus nodes on CP443-5 without repeaters

Created by: NitinW at: 2/24/2009 12:20 PM (3 Replies)

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2/24/2009 12:20 PM	Rate (1)
NitinW Posts: 17 Rating: (2)	Dear All , I willing to connect more than 100 , less than 125 , profibus nodes on CP443-5 within distance on 250 meters from CPU. Basically all these MCC cubicals with profibus interface. I have gone through theattahched manual, section , 5.2 Charactristics of DP interface. It says Number of DP slaves can be operated = 125 , but not saying anything about repeaters. DO I NEED REPEATERS for this network ?? OR , What is the Maximum Number of Profibus nodes we can have on CP443-5 without repeaters ?? Attachment 4435ex_e.pdf (121 Downloads)
NitinW Posts: 17 Rating: (2)
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2/24/2009 2:12 PM	Rate (0)
UMENCHO Diamond Expert Joined: 3/21/2006 Last visit: 3/2/2023 Posts: 10221 Rating: (1175)	Hello I think this link would answer to your question: What should you watch out for when using the RS485 repeater in PROFIBUS bus systems? regards

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2/26/2009 10:18 AM	Rate (0)
NitinW Posts: 17 Rating: (2)	Thanks Umencho. The link is saying , You require an RS485 repeater if: More than 32 stations are connected to the bus. If there is to be isolated operation of the bus segments on the bus, The maximum line length of a segment is exceeded. I didn't understand why there islimitations of 32 stations , I feel if we are managing with theline lengththere should not be any issue. Example :40 stations in90 mtr with 1.5 Mbps. Will it work , or do weneed RS485 meter after 32 nodes/stations. ?? Regards NitinW
NitinW Posts: 17 Rating: (2)
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2/26/2009 11:28 AM	Rate (1)
Mario Braganca Posts: 124 Rating: (17)	Hello NitinW In my opinion it's likea fan-out question. (From Wikipedia: Fan-out is a measure of the ability of a logic gate output, implemented electronically, to drive a number of inputs of other logic gates of the same type). So it's not only a distance issue, but also maximum source and sink currents, impedance, etc. So, in principle, with more than 32 nodes it will not work, or it can eventually work but nobody knows how long. Regards Mario Braganca
Mario Braganca Posts: 124 Rating: (17)
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This contribution was helpful to 1 thankful Users UMENCHO

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