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Read array tags with OPC (not DS) -- LV6.1

Hello DSC experts:
The Siemens OPC server to which I am connected publishes array tags and I cannot change that fact. I can read those array tags using the "Datasocket Read Double Vector.vi" but as the number of tags grows this slow method becomes unreliable. Instead I would like to use DSC but I do not see any Vi that allows me to read vector tags? Like I said I have to live with the OPC configuration as it is today hence I do not think that going through the flatten/unflatten to string method is an alternative.
Any clue?
Thanks a lot,
Chris
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Can you do any kind of array indexing when addressing the tag inside the opc server?? Something like tagname.xx or tagname[xx] where you would select a portion of the tagname array data. Could you talk directly with the VISA drivers and use a read multiple registers command instead of a DSC driver?? To my knowledge, the tag engine does not support array addressing for a tag datatype. I do use the method of flattening an array of data into a binary string and writing it to a memory tag, but the array data is created inside labview. I submitted DSC tag array datatype to a request list quite some time ago but never heard anything about it again. I wonder if a DDE connection could be established to read string data. Then do a string to number conversion. What version
of Siemens hardware/software are you using?? I think the tag engine really is lacking with respect to the capabilites of the latest OPC software. I would love to see NI directly integrate an OPC program like KEPWARE so you did not have to use the tag engine. Are you using serial or ethernet communication??
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Hello unclebump and thanks a lot for your input:
- The scout OPC server does not understand the indexing
- I never used the Visa drivers
- Yes, I agree, the NI OPC server is relatively poor and less robust than the Kepware. Another thing I noticed is that if I disconnect the physical link between the two PCs (Ethernet in my case) for more than 2 min, upon reconnection the tag engine on the LV side will not recover the communication (no more refresh of the tags and no error message! ie. tag quality is still good,...). To recover it I have to shutdown and restart the tag engine which is problematic because then all Vis that call the tag engine must be shutdown and restarted as well.
- I am using the latest version of the Siemens Scout, Etherne
t connection between the Siemens PC and the Labview PC.
- Like you I hope that the NI guys will take these requests into account.
Thanks again,
Christophe
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