Problem in reading data from an ActiveX component

[Ravinder]

Aim : To read data from a GE Fanuc PLC
Tool : Active X
Platform : LabVIEW 6.1

I have downloaded a third party active X component for reading data from a GE Fanuc PLC.

On including this Active X component in a VB program Iam able to read the requested set of data (Registers) from the PLC.

But the activeX component when included in a LabVIEW program does not give any data. A message is displayed in the indicator where the data is to be displahyed : "Value-> Array(Non Displayable)"

The VI and the OCX file is attached. What is this problem ? Is there some compatibility issue ? What should I do to overcome this problem ?

[Philip_Courtois]

Hi Ravinder,

The reason that you are not seeing the actual array is because the data is of the type "Variant" (purple wire). Variant is often used in ActiveX communication to transfer any data that is not simple. As the name implies, Variants can contain many different data types and is therefore used for flexibility reasons.

When dealing with some Variants you will have to perform a conversion into a common LabVIEW data type to see the data on the front panel. In this case the data inside the Variant is an array, so you will have to use the 'Variant to Data' function from the ActiveX palette to extract the array from the Variant (see the attached image). The data type of the elements in the array has to match the ones in the Variant, so you might have to try out different types in the Array dummy (I32, U32, DBL etc.) before you get the right results.

Good luck, you're almost there!

Message Edited by Philip C. on 05-21-2005 07:39 PM