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DP Loop Communication Error

Created by: MODICON at: 7/12/2009 5:22 PM (4 Replies)

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7/12/2009 5:22 PM	Rate (0)
MODICON Posts: 24 Rating: (0)	Hello to every one I am facing a problem I am using PCS7 V7.0.There is DP loop communication error in one area.I am using CP443-5 Ext1 and in a loop in three places I am using RS485 Reapter and on every Reapter DP2 LEAD blinking.wat can be the cause and wat is it remedy. Thanks in advance.
MODICON Posts: 24 Rating: (0)
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7/12/2009 5:58 PM

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dchartier

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Joined: 9/27/2006

Last visit: 1/19/2025

Posts: 12330

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Hello Modicon;
First, about the flickering LEDs on the repeater:

QUESTION:
Which functions do the LED have on the RS485 Repeater?
ANSWER:
The RS485 Repeater with order number 6ES7 972-0AA01-0XA0 has three LEDs.
The DC 24V LED indicates whether or not the Repeater has power.
The two LEDs DP1 and DP2 indicate bus activity. When these LEDs light it means that there is a lot of message traffic on the bus. The bus activity is high. When the LEDs blink or flicker it means that there is less message traffic (low bus activity).
Note:
The LEDs DP1 and DP2 cannot indicate any error on the bus.

So up to now you have given no valid description of your communication problem. Do you have a BUSF on the DP master? Do you have anything in the diagnostic buffer or the online hardware view that shows problems with specific slaves in your network?
In case you truly need to validate the setup of your repeaters, attached you will find an extract from the Simatic NetProfibus networks manual, covering the RS-485 repeater. Pay special attention to thesection explaining how the terminators have to be setup to allow segments to communicate with the master.
Hoep this helps,
Daniel Chartier

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Repeater.pdf (267 Downloads)

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7/12/2009 6:11 PM	Rate (0)
MODICON Posts: 24 Rating: (0)	Hello Dchartier, Thanx for the reply on the CP 443-5 Ext1 modules the red LEDs blinking on EXTF1 and on EXTF2.
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7/12/2009 6:24 PM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 1/19/2025 Posts: 12330 Rating: (2700)	Hello Modicon; We cannot look at your diagnostic buffer. You can, and you should. This is the next logical stepin diagnosing your problem. If the information on the buffer is cryptic, post it here (you can save it as a text file). We can then help you more. Hope this helps, Daniel Chartier

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7/13/2009 1:02 PM	Rate (0)
Hulzhex Gold Member Joined: 8/25/2005 Last visit: 10/5/2024 Posts: 1162 Rating: (111)	Hello MODICON, checking the diagnostic buffer of the CP you should check the DP-Master diagnostic too. There more detailed information about the status of the slaves are given. Good luck Sabine

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