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- Access returned array elements from C++
Access returned array elements from C++
Do you have any reason to think that there is something wrong with it?
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I have one more query, Index values are always same.Dynamic/Analog Types/Int[] for this tag 3 indexes are there and values are 62464 only, for first iteration and the further iteration it get changes.
Please can you clarify on this, attached image for ref.
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We do not modify the incoming values, therefore the negative values should be the values that the server has sent.
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How do I verify array tag values for QuickOPC XML demo server for tags,
Dynamic/Analog Types/Int[]
Dynamic/Analog Types/Double[]
Alternatively negative values are coming for both the tags and its my coding issue or these are actual values from server? Please refer attached image.
Thanks.
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Without going into server specific, we have therefore no way of determining whether, for example, "LXX/Wec/XXXXX31/Status/St[1]" is a good or wrong of way of specifying an item ID. It depends on the server an don its configuration. The server also may or may not have a way to specify Item IDs that correspond to array elements. It's your task to figure that out.
If you only want to access an element of an array and the server does not allow doing that using an Item ID, then, in the client code, you need to read/write/subscribe the whole array, and add a code that would handle just the element(s) you need.
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I have question on array tags if this is my array tag LXX/Wec/XXXXX31/Status/St-1, can I pass it like below to get values for this,
ex: LXX/Wec/XXXXX31/Status/St[1], this way its throwing E_UNKNOWN_ITEMNAME failure.
Therefore, I need to execute array tag like this LXX/Wec/XXXXX31/Status/St[] and get the safe-array from their I need to take index value[1], is it like that?
Please confirm if my understanding is wrong.
Thanks,
Vasanth
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SAFEARRAY* saValues = DAVtqPtr->Value.parray;
Rewrite it like this:
_variant_t value = DAVtqPtr->Value;
SAFEARRAY* saValues = value.parray;
This keeps the '_variant_t value' around until the end of the statement block.
Regards
Best regards
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Yes, I use public demo server only (opcxml.demo-this.com/XmlDaSampleServer/Service.asmx)
Yes, I do have array tags in my project. That's why before I write production code wanted to make every thing works fine.
Thanks.
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- Forum
- Discussions
- QuickOPC-Classic in COM
- Reading, Writing, Subscriptions, Property Access
- Access returned array elements from C++