Datasocket 4.0 Network Client stops if Data are with Attirutes

[vojko]

OS: W2000pro, VB50pro, DSServer40(370)

Dear friends,
I have some misterious problem with DS40.

Configuration : I have one writer with DSServer 40 on one computer and several clients on the same and other computers.

Problem:
The Clients Data on remote computers is stopped after some number of writes (???). The last value remains the same and status is : "Active connected" .

Along the normal value I use some Attributes:
CWDataSocket1.Data.Value = Value
Call CWDataSocket1.Data.SetAttribute("Quality", 192)
Call CWDataSocket1.Data.SetAttribute("TimeStamp", Now)
CWDataSocket1.Update

This doesn't happen if The writer and Client reside on the same computor !

If I do this wit
hout attributes then everything is OK.

I think the problem is With Writer ?
The same happens in Labwindows CVI 5.01.

To test: I use OneWriter.exe and OneClient.exe on one computer. The Datasocket server is on other computer.

Thank you in advance,

Vojko

[Jason F.]

Have you noticed if there is any abnormal behavior in the connection between the two computers once the dataflow stops? Can you still ping the computer running the server? Does dataflow pick-up normally again if you just restart the client? It might be helpful to create an event handler for the status updated event in order to log the connection behavior so that you can tell us whether or not the status ever updates to anything other than connected while it is running.

If you try the following scenario:

Run the server on one computer, the writer and client on another, and a copy of the client on a third.

does the client on the second computer stop reading data when the client on the third does?

We have a couple of examples that show the use of attributes with Da
taSocket in CVI, and I would like for you to try them out with the scenarios that you presented to see if they exhibit the same behavior. You can locate them at the following two links:

http://zone.ni.com/devzone/devzoneweb.nsf/opendoc?openagent&B02E52CD8D7D22568625687F005AE3EE&cat=279A3DDF188351A58625699100696455

http://zone.ni.com/devzone/devzoneweb.nsf/opendoc?openagent&5228C05FB18C24858625687F005AE3ED&cat=279A3DDF188351A58625699100696455

Jason F.
Applications Engineer
National Instruments
www.ni.com/ask

[vojko]

I used the same in VB50 sample from measurement studio. It work OK for 1. But for 3 I get stop in Client ! Maybe it is connected with the amount of traffic ???

I attached VB50 files. One is Server and the other is Client. The DSS should be on other computor !

[Jason F.]

The form for the server project is missing from the files that you submitted, therefore I can't really tell what the app is doing.

Looking at the client project's source I am a little confused by what you are trying to do in the PointerValueChanged event handlers, because you appear to be setting the slides value equal to itself, and if this slide is supposed to be bound to a datasocket connection, everytime it updates its value based on the connection it also calls the PointerValueChanged handler to alter it again. In short I don't think this is a very good idea, and is rather redundant anyway.

Did you take a look at the two samples that I mentioned in my previous post? I know that they are in CVI, but you indicated that you are somewhat com
fortable programming in it as well (CVI uses the same datasocket implementation as CWDS does, nids.dll, so that will not be an issue either). These examples can be used in the same scenario that you are inquiring about and should work rather well for your purposes.

In the end I am pretty sure that when you have multiple clients on multiple computers reading data that has attributes it does work fine with DS4.0. So really I think you should try the examples I mentioned to see if they exhibit the same behavior.

Jason F.
Applications Engineer
National Instruments
www.ni.com/ask