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MPI network and STEP 7

Created by: StavrosGR at: 6/5/2008 7:59 AM (6 Replies)

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6/5/2008 7:59 AM	Rate (0)
StavrosGR Posts: 52 Rating: (4)	Hello We have an MPI network with s7400 cpus and in one of these cpus we are going to install cp443-1 advanced for ethernet connection. The main goal is to gain access to all cpu via the cp443-1 . My question is can someone make an entry in the symbol table a variable that is in another cpu but on the mpi network. I mean in ASI you can do that. Can someone do that in MPI networks too? Thanks in advance Stavros
StavrosGR Posts: 52 Rating: (4)
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6/5/2008 8:35 AM	Rate (1)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 1/24/2025 Posts: 12330 Rating: (2702)	Hello Stavros; Depending on the amount of data (it must be small, around54 bytes per GD package for S7-400 CPUs) you could do this with Global Data exchanges over MPI. If not you will have to program S7 function (communication blocks) such as USEND/URCV (less than 200 bytes), or BSend/BRCV for larger volumes of data. To access Global data, open Netpro, click on the MPI network linking the PLCs, and right-click: Define Global Data selection. L:ook for details in Step 7 Online Help, ad in the following FAQ: http://support.automation.siemens.com/WW/view/en/430498 Hope this helps, Daniel Chartier

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6/5/2008 11:10 AM	Rate (0)
StavrosGR Posts: 52 Rating: (4)	Thanks for the immediate answer The link was very helpfull
StavrosGR Posts: 52 Rating: (4)
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6/5/2008 11:21 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Stavros, may I ask a question... what did you want to say as you said that you can do such a configuration with AS-i? I am not sure. If you want to access the PLCs by STEP7 this is no big deal but a direct access to all PLCs only with a Connection from the Ethernet is not possible. In such a case you have to collect the needed data on the PLC that has the Ethernet CP interface. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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6/23/2008 8:54 AM	Rate (0)
StavrosGR Posts: 52 Rating: (4)	I meant that in AS-i network you can directly access an input from the master station to any of the slave stations. Finally we are going to use the global data solution for accessing remote variables. Just out of curiosity . Can someone use the JAVA s7 API that siemens has provided to develop an programm tha t uses MPI interface and not the ethernet interface. It would be very interesting
StavrosGR Posts: 52 Rating: (4)
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6/23/2008 1:22 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Stavros, I hope you are aware that AS-i and MPI are totally different networks. AS-i is a mono Master system with more or less simple Slaves in it. MPI is a network of equally nodes, with usually Client - Client capability... but anyway. Sadly the JAVA interface you mentioned is only available for IT and Advanced CP’s of the Ethernet line. MPI and PROFIBUS are not capable of handling HTTP at all. HTTP and therefore Ethernetwould beessential to run JAVA in this type of connection. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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6/23/2008 1:37 PM	Rate (0)
StavrosGR Posts: 52 Rating: (4)	Yes I know they are different. After a lot of search i found the PRODAVE library that allows me to develop a communication programm with .NET environment. The only thing is that i'm not fun of the .NET environment. That is why i asked for JAVA
StavrosGR Posts: 52 Rating: (4)
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