slow datasockets

[S Salomons]

We are seeing delays of ~ 100-200 ms between when a command is sent to
the datasocket, and when the updated value is read from the same
datasocket. This is an unacceptable delay. Is there a faster method to
address the hardware?

I see the problem regardless of whether the external hardware is turned
on or not, so really my questions is about datasockets. Is there a
better method to address the hardware or is this problem something that
I cannot fix?



In case someone wants to know what the system configuration is:

I am using LabView version 6i on platform Win2K. The hardware is a
Beckhoff FC310x profibus card, running the TwinCat OPC server (v2.9.0).
The Beckhoff card communicates to a number of digital and analog
input/output modules on a
profibus bus coupler (BK3120).

[AndreOliveira]

Hi,

You should try to increase the poll rate of the OPC Server. Normally OPC Servers are configured to poll the hardware at a certain rate, you can try to increase this rate and see if the performance increases.

This poll rate will be limited by the method used to connect to the hardware, for example a serial connection will provide a slower transfer rate then, for example, ethernet.

Most likely your communication speed is being limited by the transfer rate between the OPC Server and the hardware. On the datasocket side, there is nothing you can do to increase the speed at which you write to the Server (I am assuming that you are using Datasocket VI's in a loop with no delay).

I hope it helps

Andre Oliveira

[Anonymous]

AndreOliveira wrote:
> You should try to increase the poll rate of the OPC Server. Normally
> OPC Servers are configured to poll the hardware at a certain rate, you
> can try to increase this rate and see if the performance increases.
>
> This poll rate will be limited by the method used to connect to the
> hardware, for example a serial connection will provide a slower
> transfer rate then, for example, ethernet.
>
> Most likely your communication speed is being limited by the transfer
> rate between the OPC Server and the hardware. On the datasocket side,
> there is nothing you can do to increase the speed at which you write
> to the Server (I am assuming that you are using Datasocket VI's in a
> loop with no delay).

Thanks.

So if I understand corr
ectly, datasockets can be a very fast way to
handle things in LabView, and the problem may very well be the poll rate
in my OPC server (Beckhoff TwinCat). Which means the solution I seek may
lie outside of this newsgroup.

[S S]

This apparently is not the solution to my problem. I have done more reading, and found this [1] discussion is very similar to my problem. However, I cannot find how to implement the old style datasockets.

[1] http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=50650000000800000092550000&UCATEGORY_0=_49_%24_6_&UCATEGORY_S=0