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Access to OPC Server too slow

Created by: AJTP at: 5/9/2009 1:41 PM (9 Replies)

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5/9/2009 1:41 PM	Rate (0)
AJTP Posts: 6 Rating: (0)	Hi eveybody! Description: I have develop a SCADA system. I use OPC protocol to read/write process variables. I have my S7 project in which I have created a S7 link in order to read/write process variables. From my SCADA developed in VB.NET I use the Siemens DA Automation 2.0 library to communicate with a WinAC CP5611 & CPU416 slot. In order to read/write DBs I use the S7/DP Protocol over OPC. Objective: From my SCADA (OPC Client), I would like to read/write 500 process variables the fastest as possible. Problem: When trying to read/write these 500 process variables for first time It takes over 27 seconds but the next times I read them it is immediate. Why is the first time too slow? What can I do to accelerate it? Note: I create a group and add a process variable to it only the first time I read/write the process variable. Thanks in advance, Toni.
AJTP Posts: 6 Rating: (0)
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5/12/2009 11:05 AM	Rate (0)
RPvM Posts: 22 Rating: (0)	Hello Toni, Probably it will read the variables from the PLC the first time and it has to initialise the communication. The next time they will come from the OPC cache. Just test if the changes in the PLC variables apear in your application with some delay or not.It will tell you how fast your communication really is. Maybe you can optimise a bit by grouping you data together and fetch it as an array (one block). Split it afterward in your VB application. Myself, I never use OPC but communicate directly from VB to the PLC. Takes more work and less flexible, but very very fast. Anyway, I think OPC can do better than 27 seconds for 500 variables, unless your profibus connection is very slow. (But I don't have experience with it, so I'm not completely sure) Good luck!
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5/12/2009 11:52 AM	Rate (0)
J_Bell Posts: 5822 Rating: (411)	Dear Toni, may you tell us the versions, service packs and hot fixes you may have with each of the SIMATIC Software... as long as you know it? It is hard to tell anything without knowing what version of the SIMATIC NET Software you runat your PC. By the way, do you use Symbolic or are the items you use fixed defined within your SCADA? Best regards J_Bell
J_Bell Posts: 5822 Rating: (411)
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5/16/2009 11:58 AM	Rate (0)
AJTP Posts: 6 Rating: (0)	Hi everybody again, FIrst of all sorry for my late reply I was trying to solve the problem but I haven't solved this yet. I forgot to say that the client OPC access remotely to server OPC (PC with Winac). I think the problem is that I have different versions of SIMATIC NET Software in both PCs. Following I tell us the versions of software installed in both pcs: ----------------------------------------------------------- Software installed in PC with client OPC: ----------------------------------------------------------- Automation License Manager V2.0+HF2 SIMATIC COMPUTING V3.1+SERVICEPACK 2 SIMATIC HMI TOUCHINPUT FOR SIMATIC PANEL PC SIMATIC NCM PC V5.3+SP2+HF1 SIMATIC NET PC/SOFTUWARE EDITION 2005 V6.3 HF1 B3234 SIMATIC WINAC CPU 41x-2 PCI V4.0 SIMATIC WINAC TimeSync V4.0 + SP1 ------------------------------------------------------------ Software installed in PC with server OPC: ------------------------------------------------------------ Automation license manager v3.0+hf3 simatic step7 v5.4+sp1 simatic authorsw v2.4+servicepack 2 simatic computing v3.1+servicepack 2 simatic net/pc software edition 2006 simatic winac controls v2.2 simatic winac cpu 41x-2 pci v4.0 simatic winac timesync v4.0 + sp1 simatic wincc flexible 2007 simatic wincc flexible runtime 2007 Could it be the problem (different versions of SIMATIC NET Sofware installed)? Another thing... I have another problem but I forgot to tell us. The problem appears when trying to connect remotely from client OPC to server OPC. To connect to server OPC from client OPC I call the method connect from Siemens DA Automation 2.0 library with parameters, server OPC and node (the host PC with winac and opc server configured). Then when trying to connect (client OPC to server OPC remotely) the client OPC crashes and show the following message error (I show us the following message that it is generated from my vb.net application): The object exporter specified was not found. (Exception from HRESULT: 0x80070776) Stack Trace: at OPCSiemensDAAutomation.OPCServerClass.Connect(String ProgID, Object Node) at Scada_Repair.cPLC_OPC.connect(String strOPC_Server_Name) in C:\Proj_Scada_PQ35GP\Scada_PQ35GP_Repair\Classes\cPLC_OPC.vb:line 140 Also I attach you the trace files generated by the OPC. Could it be the problem due to different versions of SIMATIC NET Software installed in both PCs? or could it be the problem due to DCOM configuration? I have checked that sometimes it connects and sometimes not. Thanks very much, Toni. Attachment opc_trace_error.zip (103 Downloads)
AJTP Posts: 6 Rating: (0)
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5/19/2009 5:13 PM	Rate (0)
J_Bell Posts: 5822 Rating: (411)	Dear Toni, I have to admit, I have no idea. Maybe this found at the OPC Foundation helps: http://www.opcfoundation.org/forum/viewtopic.php?p=5024. Best regards J_Bell
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5/19/2009 10:52 PM	Rate (0)
AJTP Posts: 6 Rating: (0)	Hi! Thanks very much for the link. It's quite interesting but it's no my case. In my case, both computers have Windows XP SP2 and now both have the same software installed: ----------------------------------------------------------- Software installed in PC with client OPC: ----------------------------------------------------------- Automation license manager v3.0+hf3 SIMATIC COMPUTING V3.1+SERVICEPACK 2 SIMATIC HMI TOUCHINPUT FOR SIMATIC PANEL PC SIMATIC NCM PC V5.3+SP2+HF1 simatic net/pc software edition 2006 SIMATIC WINAC CPU 41x-2 PCI V4.0 SIMATIC WINAC TimeSync V4.0 + SP1 ------------------------------------------------------------ Software installed in PC with server OPC: ------------------------------------------------------------ Automation license manager v3.0+hf3 simatic step7 v5.4+sp1 simatic authorsw v2.4+servicepack 2 simatic computing v3.1+servicepack 2 simatic net/pc software edition 2006 simatic winac controls v2.2 simatic winac cpu 41x-2 pci v4.0 simatic winac timesync v4.0 + sp1 simatic wincc flexible 2007 simatic wincc flexible runtime 2007 but it continues without working. However, in another line, both computers with Windows XP SP2 and simatic net/pc software 2005 all work ok. The difference between each line, is the software simatic net installed. I recently have added a IE General module and also I have an OPC Server module that is connected by a s7 connection link to CPU 416 but it still not working. I think the problem is the DCOM configuration. Before the current message "The object exporter specified was not found" I obtained another one. The first message error that appeared was "Access denied" so I modified the DCOM access right, users, and the authentication (set to none) of some DCOM applications, for example, OPC Simatic Net and something else. Now there aren't access right, I remove them so everyone can access. But, after I modified these parameters, the message "Access denied" disappared, and since then I always get the message error "Object exporter specified was not found". What are exactly the DCOM applications that I have to configure to allow two computers can comunicate over ethernet when client OPC wants to access the server OPC remotely? and what configuration do I have to set for them? Could you give me a link to a document or something similar where I can see how to configure DCOM correctly? I have seen a lot of siemens documentation about configuring DCOM but they don't work for me. The message error doesn't dissappear. Thanks in advance, Toni.
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5/20/2009 2:41 PM	Rate (0)
J_Bell Posts: 5822 Rating: (411)	Dear Toni, do you already know this Document? Using OPC via DCOM with Windows XP Service Pack 2 I guess this is the way to go for you. Be aware that both PCs need to be configured. Best regards J_Bell
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5/21/2009 8:40 PM	Rate (0)
AJTP Posts: 6 Rating: (0)	Hi! Yes, I have seen this document, and I set the configuration as appears in the document but it doesn't work. Today I have simulated the line with one laptop connected directly by ethernet to a PC. Both with Windows XP SP2 and It works so why doesn't it work in real situation in the line of the customer? After it, I think it's probably a problem of the network, DNS, or even the ethernet card. The only difference between the simulation and the real situation (the line) is that in the line both PCs are connected to a hub (not directly). Soon, maybe tomorrow or next Monday, I'll try to change the ethernet card with another one and I change his static IP (not dynamic) by another one too. Another thing, in both cases, simulation and real situation (line), no firewall is enabled. I disabled it to avoid problems and the PCs always have the same IP. The IPs are static, e.g. one PC always have the same IP and the same for the rest. Thanks in advance.
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5/26/2009 11:58 AM	Rate (0)
gary2919 Bronze Member Joined: 9/10/2007 Last visit: 10/19/2023 Posts: 24 Rating: (2)	Hi, This may not help in your case, but just a suggestion.. Is it possible under your connection settings to change from where the data is read, from cache, to directly to device? I did that once for an OPC link i had setup :)

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5/26/2009 5:51 PM	Rate (0)
J_Bell Posts: 5822 Rating: (411)	Dear Toni, well, in this case I just may start to guess. Is it possible that due to certain installation restrictions of your site the PCs may received certain Software or settings preventing the DCOM capability from working... or at least changing some settings which usually allow the DCOM communication? Best regards J_Bell
J_Bell Posts: 5822 Rating: (411)
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