Browse OPC DA Items - Error Syntax doesn't conform to the server

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Bubba
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Browse OPC DA Items - Error Syntax doesn't conform to the server

Post by Bubba »

Hello,

I am using a UA Gatway OPC UA Server to a UA Gateway OPCUA to OPCDA configuration to obtain data directly from T3000 communications modules (OPC UA). The UA Gateway's DA server is the connection to which my PI OPC DA client connects. We have some minor issues.. But when I try to manually load items (URLs) the DA Server on my side of the firewall ... I can view the items. However, when I need to browse a significant number of items, say 300+ or 500+ ... using Matrikon OPC Explorer ... when I go to add them, it tells me the items syntax doesn't conform to the server ... but if I take those same itemIDs (URLs) and add them a few at a time, almost all of them work.

Sometimes just I want to browse all 3300 tags to verify everything is working ... in that case I get at most 15 or maybe 20 items working. All the rest fail validation because of this syntax issue. But again, if I chop it up into small enough blocks, I can browse almost all 3000 of the tags.

The error code is 0xc0040008

Thanks,
Bubba

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Support Team
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Re: Browse OPC DA Items - Error Syntax doesn't conform to the server

Post by Support Team »

Hi,

in OPC UA a server may have limits on different operations, especially on the "browse" the number of returned elements can be limited. The UA Client can limit the number of retured BrowseElements to protect himself, but also the server can limit the number and indicate "more elements available", forcing the client to browse again (browse-next, with continuation point) to get the rest.

The "Invalid ItemID" error can have mutliple reasons (including timing issues), because the subsystem (in T3000) may have archived the data already, depending on how many you ask for and which/how many properties you are requestiong this may take a while (on first use). Your DA Client typically does not respect the limits and timeouts, because in old DA all calls where synchronous (take as long as it takes). In cntrast thereto in UA every call is asynchronous, and timeout must be set properly.

The UaGateway is transpparent, if the MatrikonExplorer asks for browse including all properties, the UaGateway must not only browse, but also read multiple properties of all the items, which may take longer than the configured timeouts.
Best regards
Unified Automation Support Team

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