No data retrieved from a OPC server when usind DatasocketRead VI

[zenou]

Hello,

I'm unable to retrieve data from an Eurotherm OPC server (LinOPC) using the DatasocketRead VI in LabView 6.0

The execution of the VI seems to be OK (erreur code is 0 (=OK)) , but the result is not correct.

Instead of a real, I get  4 attributs (Quality, Timehigh, Timelow, et Timestamp) (see attached pictures)

I do not have particular problems when §I use another OPC clients like OPC Scope

[mehdi.afif]

Hello.

Does the behavior you notice occur just for the first read value or does it always occur?

Have you got the same result if you run LabVIEW examples?

Mehdi A

NIF AE

[zenou]

This behavior always occurs. The result are the same, excepted that the value TimeLow increases rapidly.

I have the same results when using the Datasocket VI examples.

[mehdi.afif]

Hello.

I noticed in the print screen you sent in your previous post that you didn't choose any data type as an input of the DataSocket Read function.

I think you should specify the data type you are attempting from the OPS server.

Regards

[zenou]

According to the datasocket_read VI, the input 'type' should be a variant.
I didn't fully understand what is a variant, so I connected a constant to this entry (as done in the DS_Reader exemple VI)

As a result, I have now a single value, which is:
0.000E+0 if I connect a REAL (EXT/DBL/SGL) constant
0 if I connect a INTEGER (I32/I16) constant

So the type is recognized for execution, but the value is still wrong
According to the OPC server, a value of about 22.5 is expected, in DOUBLE format.

I have another proof that the OPC server receives a query from labVIEW: The query counter increases each time I run the VI