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PC-station to PC-station OPC connection possible.

Created by: Jesper Pedersen at: 6/23/2008 10:54 AM (9 Replies)

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6/23/2008 10:54 AM	Rate (0)
Jesper Pedersen Posts: 279 Rating: (30)	Hi. This might seem to be an odd request. The background is that we have a customer that wants to fetch information from our machine via an S7 connection in his PC. Problem is that the machine is completely standardised and we do not want to modify it for just one customer. We have a PC with some special programs, including an SQLdatabase that connects to the machine via Simatic Net. All the information that the customer wants is already on the PC and the database. The obvious answer to the customer is to fetch the information from the PC via SQL, but he dont want to do that, he wants to fetch directly from the machine via Profibus and an S7 connection on his PC. As a possible solution, that would mean that our customer could keep his way of doing things, and we can keep our machine and database PC to handle such things, is it possible to setup an S7 connection from PC-station to PC-station ? I can indeed setup such a connection in NetPro, but how is data exchanged ?
Jesper Pedersen Posts: 279 Rating: (30)
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6/23/2008 12:17 PM	Rate (1)
J_Bell Posts: 5822 Rating: (412)	Hello, well, you are right. You can configure such a Connection but the issue is that you can not "just" access the SQL Database just as it would be on Ethernet. If you configure a S7-Connection you can use the virtual DB available in the OPC Server to store or retrieve Data on/from. I think this would be the easiest way. The main issue for you would be, as far as I think that you have to change your PC Program, because you have to provide the data in your whished way in the DB, this is your job then. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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6/23/2008 1:41 PM	Rate (0)
Jesper Pedersen Posts: 279 Rating: (30)	Thanks for the reply mysterious mr. "J". "Virtual DBs", that sounds interesting. How do I setup that ? As for populating the OPC server with data from the SQL database, then that is my problem, and I can take care of it, if only there is an OPC connection and some symbols.
Jesper Pedersen Posts: 279 Rating: (30)
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6/23/2008 5:30 PM	Rate (1)
J_Bell Posts: 5822 Rating: (412)	Hello Jesper... check the manual: Industrial Communication with PG/PC Volume 2 - Interfaces Programming Manual and there the chapter: 2.5.9 Server service. there you see that you get a DB 1 with up to 64 kByte of data with the S7 OPC Server. This Server DB could carry up to 64 kByte to your remote PC over S7 Communication. The only problem I see, but I guess it will be none for you, is that you will get no symbols... this is not part of the PC Station parameters. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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6/24/2008 8:59 AM	Rate (0)
Jesper Pedersen Posts: 279 Rating: (30)	Excellent. It sounds just like what I need. I shall give it a test. Thanks again J_Bell.
Jesper Pedersen Posts: 279 Rating: (30)
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6/24/2008 10:45 AM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	You're welcome Jesper... Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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6/24/2008 3:38 PM	Rate (0)
Jesper Pedersen Posts: 279 Rating: (30)	OK, now I have made a test. The good news is that a fully specified connection works fine. The bad news is that an unspecified connection does not work. I specify the IP address, rack=0, slot=2 (OPC server has index 2). I am hoping for being able to tell the customer to setup an unspecified connection. This is the easiest for both parts ("easy" being of importance here !) Any ideas ?
Jesper Pedersen Posts: 279 Rating: (30)
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6/24/2008 3:53 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Jesper, I fear a PC Station is in this point not comparable to a PLC. The local DB is, as far as I know, only available in case of a fully specified S7 Connection. But to tell you the truth, I see no problem in that. Well, if you want to access the PC dynamically from various PLC’s this could be a problem but the fixed configured S7 Connection is no problem, at least not in my mind. If I see the former S5 times you also had to exchange the TSAP’s and Addresses to get online, even with Fetch Write. Even flexibility has its borders. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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6/25/2008 8:52 AM	Rate (0)
Jesper Pedersen Posts: 279 Rating: (30)	If it has to be this way, then OK. The problem is that the other partner is a 3rd party. So I cannot make a completely integrated project. I think that maybe there can be a way in using two projects with "dummy" partners in each project.
Jesper Pedersen Posts: 279 Rating: (30)
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6/25/2008 11:04 AM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Jesper, yes... I guess this would be the way to choose. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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