How to read All FP-Channels via DataSocket?

[reke]

Hello specialists,

as default the Fieldpoint Explorer (and so the FP-OPC server also) provides an All-channel. By this channel you can read the values of all 8 channels of a fieldpoint module.
I tried to read this channel with DataSocket_Read.vi from LabVIEW. For datatype I tried Variant an an array of dbl, but both doesn't work. Is it possible to read the FP All-channel via DataSocket?

After that I tried to read the FP channels as single channels one by one. I had done this in a for-loop. But the I got an error 56 many times or the application hung. It seems that some threads got no CPU-time. Has anyone a solution or explanation for this problem?

Thanx in advance,
Michael

[Aaron_G]

No. If I recall correctly, it is not possible to read an "All Channel" of analog values via datasocket. The all channel will actually only contain the first element of the array and not be a full array.

As for the second problem, what version of LabVIEW RT are you using? LabVIEW 6.0.3 DataSockets did not have the ability to multiplex Lookout URL's, additionally, the DataSocket.vi's consumed a decent amount of memory for each instance of the VI and could cause memory errors. LabVIEW 6.1 DataSockets are able to multiplex the Lookout URL's and are much less memory intensive.

Regards.
Aaron

[reke]

Thank you, Aaron, for your quick answer,

I think you are right concerning the "All channel". Thats what I got. The "All channel" contained only the first element.

Concerning my second question: I use LabVIEW 6.1 (not RT). But you are talking about a Lookout URL. I don't use Lookout. My URL's are "opc://localhost/National Instruments.OPCFieldPoint/FP Res\FP-TC-120 @3\Channel 0" to "...\Channel 8" Is this right? And how do I get the DataSockets to multiplex the URLs? Or are they doing this automatically?

Best regards,
Michael

[Aaron_G]

The FieldPoint OPC Server only publishes the first item in an "All" Channel analog array. That is the designed behavior.

I do that LabVIEW 6.0 Datasockets could not multiplex the Lookout URL's, but I do not know about OPC URL's. If you feed in multiple URL's to the same DataSocket Read (or write) through the use of an indexing loop and you actually get the different channels, rather than the same channel repeatedly, than the DataSockets are properly multiplexing automatically.

The Lookout URL's don't necessary mean that you are using Lookout. When using DataSocket URL's, the keyword "Lookout" tells the DataSocket to use the National Instruments Lookout Ethernet protocol which is used by Lookout 4.x and later, FieldPoint Ethernet modules a
nd LabVIEW Data Logging and Supervisory Control Module. For more information on using DataSockets to directly talk to FieldPoint Ethernet modules, read the following article:
http://zone.ni.com/devzone/conceptd.nsf/2d17d611efb58b22862567a9006ffe76/a6617392b393c4b886256acb0053aebe?OpenDocument

Regards,
Aaron