MODBUS/TCP very slow execution

[acxysty]

Dear all

We are new user to Labview and to LabVIEW forum.

We are designing a LabVIEW application that interacts with PLCs.

We are trying to exchange information between a PC/labview and a PLC. Both support the MODBUS/TCP protocole. We have designed the 2 programs easily, the PC/LabVIEW one being easily made with VI Library.

We first the PC/LabVIEW as a cleint and the PLC as server and it works perfect. It is quite fast as it takes less than 1 second.

We test the reverse configuration ie PLC as client and PC/LabVIEW as server. Of course we use different programs there and monitor the MODBUS/TCP frames with WireShark.

It works also but the execution on the PC/LabVIEW is very long (in the debug mode) : it takes 5 secondes to execute the Write Multiple Register function ( 2 data to write) to prepare the response frame and to send it back. It is very nice to see the animation on the diagram but why is it so long ? This long time frame is a very big problem for our application.

We re not sure to know where to dig in !

Thank you in advance for your help.

Regards

Thierry

[tst]

If the execution takes too long in highlight execution mode, just turn it off by clicking the light bulb icon in the toolbar.

That mode is there for debugging, which is why it causes the VI to run slowly. It's not supposed to be used during the time the program is actually used, so why do you have it on at all?

[acxysty]

Thank you tst,

We will try that on monday and keep you informed.

Regards

Thierry

[RavensFan]

It sounds like you need to learn more about the LabVIEW development environment if you were confused about the slow speed of highlight execution.

I would recommend looking at the online LabVIEW tutorials
LabVIEW Introduction Course - Three Hours
LabVIEW Introduction Course - Six Hours

[acxysty]

You are right. It was a good idea !

Regards

Thierry