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Redundant Stratus Server & S7400 F/H Communication

Created by: BEK (AIS) at: 9/23/2008 1:54 PM (4 Replies)

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9/23/2008 1:54 PM	Rate (0)
BEK (AIS) Member Joined: 4/8/2008 Last visit: 6/19/2024 Posts: 2 Rating: (0)	Hi, We have a customer with an existing SCADA system running on a PC supplied by Stratus Technologies. This is a dual redundant system running Windows 2003 Server and comes as two 'slices' (i.e. individual PCs) running as a hot standby pair. Each slice has two Ethernet network cards, so there are four Ethernet cards in total. The system uses Intel Teaming software configured in fault tolerant mode to pair one network card from each slice to provide a single network connection to the outside world. This is done twice, providing two external connections: if we number the Ethernet cards in one slice as 1 and 2, and the second slice has cards 3 and 4, then cards 1 and 3 are teamed to provide one external connection, and cards 2 and 4 are teamed to provide the other connection. These connections are on different subnets: one communicates with the plant I/O, the other with SCADA clients. We are adding dual redundant fault tolerant Siemens S7-400 F/H PLCs to this system. Communication between the SCADA server and the PLCs will be over Ethernet and will be using an OPC server on the SCADA server. Ideally, we would like to provide full redundancy, so if one of the PLCs goes offline, the SCADA server will communicate with the other PLC. This can be provided by using S7-Redconnect running on the SCADA server. But reading some of the other FAQs, it appears that this requires Siemens PCI network cards (e.g. a CP1613). Is this a just recommendation or an absolute requirement? I understand that you would not guarantee operation over non-Siemens network cards, but is it possible? We already have four network cards in our server, and adding two more, one for each slice, seems excessive! If we did add the Siemens PCI network cards, they would have to meet requirements for them to run in the Stratus PC, there are two: a) the cards have to be on the Windows hardware compatability list b) the cards have to support the Intel teaming software Do Siemens provide PCI network cards that meet these requirements? As an alternative to full redundancy, we could link the SCADA server to just one of the Siemens PLCs. Then we would need neither S7-Redconnect nor new Siemens network cards. This might be acceptable, as there are HMIs linked via Profibus to the PLCs, and the SCADA server link to the PLCs is not a critical part of the system. If we did this, could we configure the Ethernet modules in both PLC racks with the same IP address? Then, in the event of long term loss of one PLC, we could just connect the second, functioning PLC to the Ethernet network. Does anyone have any other suggestions? Has anyone connected a Stratus server or something similar to F/H PLCs before. It would be wonderful to hear from someone who has! Brian

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9/23/2008 2:13 PM	Rate (0)
JMJ Posts: 487 Rating: (45)	If you use 400H, redconnect is the best option to have and yes, it is a must to use Siemens ethernet cards. Redconnect configuration is not supported on generic NICs. Kepware has some options by keeping two OPC servers on two different PCs or even 2 virtual PCs and then using redundant master option from kepware. Check the link below http://www.kepware.com/KEP_KB/default.asp?ToDo=view&questId=324&catId=99
JMJ Posts: 487 Rating: (45)
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9/23/2008 6:09 PM	Rate (0)
BEK (AIS) Member Joined: 4/8/2008 Last visit: 6/19/2024 Posts: 2 Rating: (0)	Thanks Jomy, I've looked at the Kepware RedundantMaster option, very interesting. But I'll need to use two PCs. That's certainly not a show stopper, but it would be better if I could run everything off the single SCADA server - it is dual redundant after all! Brian

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9/23/2008 8:50 PM	Rate (0)
JMJ Posts: 487 Rating: (45)	You can consider putting two virtual machines in the SCADA server (obviously it is going to eat some resources of your server, but you can alway beef-up the server). The virtual machines can be on the same network. Have you seen this link in kepware which gives more info on RM? http://www.kepware.com/Products/RedundancyMaster.htm. Also check the diagram attached from the page (Local machine redundancy). In this case one of the OPC server is on the same machine as the RM. So can't you have one slice as primary OPC server and the other as secondary OPC server and then configure 1RMs eachonboth slices? I do not know your SCADA supports this.
JMJ Posts: 487 Rating: (45)	Last edited by: JMJ at: 9/23/2008 8:51 PM Oops! Forgot to attach JPEG
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10/5/2008 1:21 AM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Hello, I would like to add some points. First of all... Teaming is not redundancy. Teaming means to improve the throughput but not offering any redundancy. The CP 16X3 is the hardware to run S7 Redconnect on. The use of other NIC’s or the Teaming function provided by Intel for Intel Cards is not supported. The Software driver is not NDIS based, therefore it will not be noticed by Microsoft for compatibility issues at all.So, it is a totally other base. Please excuse my late response. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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