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slow data tranfer to VB6

Created by: matholton at: 7/25/2007 12:59 PM (5 Replies)

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7/25/2007 12:59 PM	Rate (0)
matholton Posts: 37 Rating: (0)	Hi there, I'm currently working on a very old legacy WinCC/VB6 system. The VB reads about 500 tag values from WinCC via the "WinCC-Runtime-Project", using the getValue(TAG NAME) function. However this puts great pressure on a particular process named CCMCPA~1.EXE (as it appears in Task Manager). The customer requires faster updates to the database (which is handled by the VB). But in doing this I have to get values more frequently from WinCC. So, my question is: Is there a quicker way of transfers multiple Tag Values from WinCC into VB6? Perhaps by passing a pointer to an array and have WinCC fill it up on it's side, instead of multiple calls to getValue? Any help, as always, would be greatly apreciated. mat
matholton Posts: 37 Rating: (0)
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8/8/2007 11:56 AM	Rate (0)
matholton Posts: 37 Rating: (0)	Bump
matholton Posts: 37 Rating: (0)
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8/9/2007 6:32 PM	Rate (0)
Salma Gold Member Joined: 9/27/2005 Last visit: 11/27/2007 Posts: 1398 Rating: (151)	Sounds like you are using ODK functions to get the data into VB, is this right? If so a much faster way is to use OPC. WinCC provides an OLE automation wrapper for OPC DA which you can use directly in VB to connect to WinCC and poll tags synchronously, asynchronously or on callback basis. If you need, there is a simple example of using VBA (in Excel) to make this connection. There are also example programs on the OPC Foundation site. Salma

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8/10/2007 2:17 AM	Rate (0)
Dec Gold Expert Joined: 5/19/2006 Last visit: 12/3/2024 Posts: 549 Rating: (107)	matholton So, my question is: Is there a quicker way of transfers multiple Tag Values from WinCC into VB6? Perhaps by passing a pointer to an array and have WinCC fill it up on it's side, instead of multiple calls to getValue? Any help, as always, would be greatly apreciated. mat Well I think there is no quicker way to transfer tags values from DataManagerRT to your VB application other then maybe using OPC, see Salma response. I am not sure about the performance gain though. The performanceissues you have with VB-ODK in your application is due tolimitations of "WinCC-Runtime-Project"that only wraps 2 synchronous functions Get(Set)Value of DataManagerRT IVar2 interface Read(Write)Var with only one tag per call. Dec
	Last edited by: Dec at: 10.08.2007 07:28 Last edited by: Dec at: 10.08.2007 04:11 Last edited by: Dec at: 10.08.2007 02:26
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8/10/2007 5:05 PM	Rate (0)
matholton Posts: 37 Rating: (0)	Thanks for the replies :-) I'm not familer with OPC at all - where is a good place to start? What the heck is it? I've made some progress by combining many of the boolean values into bits within a 2-byte word, sending those to VB and extracting them there. But, yeah, CCMCPA~1.EXE is still using up to 70-80% CPU! And this is on a 1.6 Mhz CPU!
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11/7/2010 5:04 PM	Rate (0)
Tash Posts: 3 Rating: (0)	Did you ever get it working? What was the format for OPC Items to read the WinCC data?
Tash Posts: 3 Rating: (0)
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