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Cba Communcation between S7-315-2PNs

Created by: finaldata at: 4/29/2008 3:46 PM (6 Replies)

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4/29/2008 3:46 PM	Rate (0)
finaldata Posts: 4 Rating: (0)	Dear Sirs: I have a serious problem about Cba communication, The situation can be showed in the attached document, there are two or more S7-315-2PN in the workshop, they are located in the difference network section ( 192.168.22.120; 192.168.31.13 etc), now I have build up the Cba components and build up the communcation via IMap, but the response time is very long when the 2 component located in the difference Switchs, someone told me that it is normal because the SCALANCE X 414-3E, it it right? Attachment help.JPG (340 Downloads)
finaldata Posts: 4 Rating: (0)	Last edited by: finaldata at: 4/29/2008 3:49 PM
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4/29/2008 4:12 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Hello, I fear the issue here is not the reaction time within the SCALANCE X414-3E because especially with PROFINET CBA this is not such a big issue. What lets me think is your Wireless Connection. Have you ever tested how long a Ping takes from one Partner to the other one? CBA is a highly loaded protocol, DCOM is used there. So it might use a lot of traffic just to transfer a view Bytes. First of all I would try to see how long the reaction takes on your setup. If the time is above 10 - 20ms this could be an issue. Have you ever spend a thought on the alternatives in your situation? Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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4/29/2008 4:17 PM	Rate (0)
finaldata Posts: 4 Rating: (0)	Dear Mr.Bell: Thank you very much for your attention, the PING time from component to another is about 5 ms.
finaldata Posts: 4 Rating: (0)
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4/29/2008 4:22 PM	Rate (0)
finaldata Posts: 4 Rating: (0)	Dear Mr.Bell: I have tested the respones time when the two components located in the same network section such as 192.68.22.12 and 192.168.22.13, the response time is about 50ms, it can meet the request, but if the two components located in the difference netwotk section, the response time will be more longer , the response will be more than 1s, and the PING time will be 5 ms, someone told me that maybe the problem is the rout fuction of SCALANCE 414-3E, can the rout fuction of SCALANCE 414-3E support Profinet Cba? thank you evry muc! B.R Wang weiliang
finaldata Posts: 4 Rating: (0)
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4/29/2008 4:48 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Wang weiliang, I am sorry, but I can not imaginea Ping response of 5 ms over two Router. But it is true the Response time if you use a Router is much higher, this is easily explained. Each Telegram that is transferred over the Router has to be checked in that way that the Destination Network is within or outside the local Network. If the Destination within the Router it forwards the Telegram to the switch that decides which Port the Telegram can be forwarded to. So this will certainly take a lot of time. I wonder, why do you need to use different Networks? Do you use more than 254 activeNodes in one logical Network? Alternatively I would strongly recommend to use One Network for the Networking devices such as Hubs and Switches and one for the activeComponents, this lowers also the amount of IP Addresses used. If you want to connect Components on different sites with CBA you will have to be aware of the long response time. Think about it, CBA has compared to other Protocols a huge Overhead of Management data. All this information has to be transferred over the same link too. The ideabehind CBA is it to interconnect logical Moduleswhich areused repeatedlylocally. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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4/29/2008 5:03 PM	Rate (0)
finaldata Posts: 4 Rating: (0)	Dear Mr.Bell: Thank you for your advise, But actually , In the application, there aremore than 10 components in the workshop,in order tomanage the netwrok, the customer have build up difference logic netwrok for differenct fuction section , so, they need use Cbacomponents in difference logic network. and acorrding to your statement,it is not so good use Cba solution in the application, so, if I use the OPEN TCP connection as you mention before (Generating the Connection Data for the open TCP/IP Communication using the Open Communication Wizard http://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&objid=25209116&caller=view) canthe response timebecome shorter? andif I use a PC ping the PLC located in the difference logic network, the PING time will be 5 ms, it is true, B.R Wangw eiliang
finaldata Posts: 4 Rating: (0)
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4/29/2008 5:32 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Wangw eiliang, well... I believe you. I would say it is well worse a try. I believe that the Reaction time will be much shorter with the TCP Connection than with CBA. Please try it. I am convinced you will be surprised. I believe that the location of the separate Tasks in separate Networks is useful, butas far as I remember it was thought that way that the CBA Interface is the single interface to the outside of the local Task isle and only used for this task alone. So it was thought that for all other tasks other Interfaces would have been used. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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