8/22/2019 3:28 PM | |
Joined: 10/24/2017 Last visit: 3/16/2024 Posts: 4 Rating: (0) |
Hi all Siemens user community. I have an S7-200 Profibus network that is as shown in the attached sketch. My problem is that my SCADA PC is failing to reach out to nodes with station addresses 4,5 and 6. That is the SCADA is only able to read or communicate with Station 2 and not beyond. Bus terminations are ON at node addresses 2 and 6. If I connect a PG device on Node 2 ,port 0 and check for available connections,I am able to reach out to station 4,5 and 6. But on the listing-station number 2 is not listed.If I connect a PG device on any of nodes 4,5 or 6 and check for available devices,I can read any other device in that segment except Address 2. What could be the problem guys? AttachmentProfibus Network.pdf (233 Downloads) |
8/22/2019 8:06 PM | |
Joined: 9/27/2006 Last visit: 10/8/2024 Posts: 12284 Rating: (2685) |
Hello Tap; Termination resistors should be ON only on the first and last stations on the Profibus network. On your sketch, this would the PC and station #6. Say the termination is ON on station #2. Then from the PC's point if view the bus terminates at station #2, and nodes 4, 5 and 6 cannot be reached. If you the connect to station #2 with a PG, you cannot see the PC but the other nodes are accessible. One question: why do you show Port 0 and Port1 on station #2? Is it connected differently than the other S7-216s in the network? Normally we would expect an EM 277 as a Profibus slave module on each S7-216 in order to have them connected to a Profibus network. In every Profibus network there must be a master, and since S7-200 can only act as slave on the bus, the SCADA PC must act as master (even if it is class 2 master). https://support.industry.siemens.com/cs/us/en/view/19839489 In any case, one visual trick to remember is that end nodes only have one Profibus cable on their connector; these are the nodes that require active terminations. All other stations have 2 Profibus cables on their connector, one going in, one coming out, to make the daisy-chain connection; these nodes need the termination to be OFF. Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 08/22/2019 20:10:56Last edited by: dchartier at: 08/23/2019 01:08:39 |
|
8/25/2019 8:48 AM | |
Joined: 10/24/2017 Last visit: 3/16/2024 Posts: 4 Rating: (0) |
Good day dchartier Thanks for the response. The bus termination is ON at both CP5611 and port 1 at station #2. And again the bus termination is ON at port 0 node #2 and at station #6 to make 2 segments in the network. The system has been working like that. I am not sure how it has been programmed. Now the PC can reach out only to node #2. I have attached screeshorts for the communication sub-routines for all the nodes and have verified them to be active using a status table. AttachmentComms Sub-routines.zip (219 Downloads) |
Follow us on