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Step7 programming via ethernet on what OSI layer?.

Created by: ramiv at: 5/7/2007 9:35 AM (4 Replies)

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5/7/2007 9:35 AM	Rate (0)
ramiv Posts: 55 Rating: (1)	Hello, i am using currently VPN connections for remote programming S7 300-s via CP343-1 Lean. However, now the client wants to get rid of VPN connections, and they are offering a web based solution (Forte netservices) where i go into a web page, and after entering user id + password i should be able to remotely connect to the plc:s. The portal provider is not familiar with Simatic at all, they have set up the system but i cannot connect to the plc-s via Step7. They say that the system works at OSI-layer 7, now i tried to find this information from Siemens web, but did not succeed. On what OSI-layer does the Step7 programming protocol work?.
ramiv Posts: 55 Rating: (1)
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5/8/2007 6:33 PM	Rate (0)
Calm_down Posts: 324 Rating: (30)	Hello ramiv, well the speech about ISO Layer 7 is really simple from this company, because Layer 7 says only that it uses the Application Layer. Well any Program that communicates works on Layer 7. This means actually nothing at all. If you want to communicate over the Internet you need direct Access to the PLC over the Port 102, of any way. So, the best would be a Router on the Network that works over the Port 102 and allows you to access the PLC. This will surely not work on HTTP or HTML basis. VPN is the best and as far as I know only really working solution. SSH will work too, but with a HTML Solution... I doubt it. Stay calm.
Calm_down Posts: 324 Rating: (30)
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5/8/2007 8:22 PM	Rate (0)
ramiv Posts: 55 Rating: (1)	Hello, and first of all thanks for participating, Calm_down. I've done some research, and found out that maybe the step7 is not the problem at all, instead Symantec antivirus and XP-s own firewall are not working with the portal system as they should. Thankfully i was able to get in contact with a person who administrates the 'portal' system, and he surely knows how it works and what we can test and how. Previously i only spoke with people who sell + use these systems, and they knew nothing when i asked. So when i get remote desktop connection working for the MMI PC on that site, then i will try again the Step7. VPN is indeed really nice and useful way of doing remote programming, but this particular client (a pulp- and sawmill company with many factories in several countries) says that it costs them too much, and it is complicated too with many users / sites. P.S. I found out that Step7 communication works on layer 4 at the ISO/OSI stack.
ramiv Posts: 55 Rating: (1)	Last edited by: ramiv at: 08.05.2007 20:29 Last edited by: ramiv at: 08.05.2007 20:28
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5/10/2007 12:15 AM	Rate (0)
Calm_down Posts: 324 Rating: (30)	Hello, just to mention... the STEP7 Software uses the S7 Protocol, which is a Layer 7 Protocol. Just to mention. Stay calm.
Calm_down Posts: 324 Rating: (30)
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5/10/2007 7:07 AM	Rate (0)
ramiv Posts: 55 Rating: (1)	Hello, so then i misundestood the diagram on the Simatic manual and it is layer7. But into the problem, the solution was this: Microsofts Knowledge Base article #884020 states that with XP SP2 they had created a problem that if local communication goes through any other ip than 127.0.0.1 it does not work. In this case the communication between local software (S7 and remote desktop + pcAw) and the SSL tunneling client goes through 127.0.1.3. So installing update #884020 solved the problem. Raimo
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