Datasocket OPC write speed

[sdudeck]

Hello,

I am struggeling with the massively changing runtime of the "datasocket write VI" within LabVIEW (12.1f5).

I use a Siemens.NET OPC server to communicate between a LabVIEW program (doing some measurement tasks) and a S7-PLC. From time to time the LabVIEW-program sets some values on the OPC to make the S7 move some actuators.

What I have seen so far from my logfiles is, that calling the "Datasocket Write VI" takes between 20 ms up to 1000 ms for writing only 4 bytes on the very same connection. There are no changes like closing and reopening of the connection inbetween, but there are about eight other connections, to other adresses on the OPC server, open at the same time.

So I have several questions:

1. Are the Datasocket VIs reentrant VIs at all?

2. Does somebody know this behaviour of fluctuating runtimes of this write VI? Is this due to some mechanism in LabVIEW or should I better look on the OPC and PLC side?

Thanks a lot,

Sven

[Jesse_D]

Hi sdud, 

1) no. 

2) Data sockets run in a single thread and in the UI thread. My guess is that you are interacting heavily with the computer or the other connections are running and taking priority. The DSC module shouldn't have this behavior. 

[sdudeck]

Hi,

thanks for the fast answer - I think we will try it with the DSC.

Sven