Dear All here my situation :

I have 10 DP Devices, and they are connected to my PLC using Repeaters and the attached schematic show my connection.

the problems i faced is :

1- I only can see DP 19 and DP 20

2- if I reconnect the cable of DP (11,12,13) to R1 in the place of Cable (18,19) then PLC will be able to see Address 11 only, and if I change the address of 12 or 13 to 11 I will see it also but cannot see any device with address 12,13

I hope you understand me and can give me help.

regards;

Hello.

Did you check all the connections, terminators, pay attention also on cable crossing.

I checked all termination , if there's two cable on the connector i put it off if there's only one cable i put it on, im sure no problems with this point

what i feel is that only the first repeater working well while i can see that there's synch between first and second repeater and between seconed and third one.

Assem Saffarini

and what you mean by cable crossing ??

 I mean crossing the green/red of Profibus cable wires inside DP-connector (invalid connection).

Best thing to do:

Disconnect ALL, just leave the repeaters connected in cascade.

Then start connecting one slave and check it, then anotherm then another, etc.

You will be able to catch the problem more easily.

Hello,

Please check the manual in this link. In section 5.4, check the various configuration options for Profibus repeaters.

SIMATIC RS 485 Repeater

http://www.profibus.com/uploads/media/03_PROFIBUS_Design_good_practices.pdf

For more than one repeater in the network, don't connect them in star! Connect in daisy chain 

Hope this helps

Dear Assem,

Have a look to the attachment, i think its a matter of terminating resistor switches.

please adjust the terminating switches as shown in the attached picture!

hope it will solve your problem.

Ashish Singh