Variant in Variant of a shared variable

[kahlenberg]

Hello,

I am trying to read some Tags in a Siemens S7-1200 PLC over NI OPC server. I can read them in NI-DSM (Distributed System Manager). However, I can not read or write them in Labview. I generated a shared variable event loop which will run when a  variable changes. I get always Variant in Variant as Value which is not correct as I want to convert it to a data type. (See attached image)

How can I correct it?

[Sam_Sharp]

Use 'variant to data' to convert it to the appropriate data type (it looks like a numeric?).

[kahlenberg]

Did you see the image? Variant to data but which data? Data is also variant. I have to make variant->variant->UInt8 which seems not good and not correct. Tags are UInt8. Normally in probe windows I see <variant:254> for byte variables. But what does it mean <Variant:<Variant:233>> ?

[Sam_Sharp · Accepted solution]

It doesn't matter, this works:

[kahlenberg]

O thanks, it works. But I wonder why are there 2 variants inside each other.

[Sam_Sharp]

It is quite common for a function/property/method to return a value as a variant if the data type is unknown at runtime (e.g. getting a control value for a generic control).

Is your shared variable a variant? If so - the event data converts that to a variant (even though it is already a variant) because you might have registered for events for different shared variables that might be of different data types so it returns as a variant so you can convert it to the correct type (based on the 'data type' event data item).