Dynamic Event LabVIEW

[R.Kaszubiak]

Hello,

I post this comment because I have questions about "dynamic event" in Labview and Veristand.

LabVIEW allows user generate dynamic event but :

- What is really a dynamic event?

- What is the mechanism used by Labview to manage a dynamic event?

It's TCP-IP communication, network streming ....

[Norbert_B]

"Dynamic" means: can occur at any time.

So essentially, the event source and the code which executes in case the event occurs have to be known before starting the program (so during development time).

Since you mention Veristand, i think you will work with a real time system.

User events are possible on real time, but you have to have a deep knowledge on the processes running on the rt. So this is definetly not for beginners....

Norbert

PS: Events are managed with an event queue feeding the event structure. Events are handled by interrupts which is the main reason why they can kill determinism on RT systems.

[R.Kaszubiak]

Thanks for the answer.

Yes, I develop application both on Windows and RTOS.

I would try to create my dynamic event to establish a communication between a custom device and a host application.

I know Veristand API allows user to send a message to a specific custom device and get the answer but what i want to do is the opposite : the custom device send a dynamic event and the host application get it.

[Norbert_B]

Software events can only be handled within the application context itself. So you cannot create an event on the RT system which is handled on the host.

Regarding your request with Veristand:

Veristand does not define any event based communication from the RT to the host. But you can create a channel in your appliction which is "set as event". The host has to poll for this channel value (so not really event based) and in case that the value changes "fire" the reaction.

Norbert

[R.Kaszubiak]

Are you sure?

I take two screenshots :

- First :the diagramme of the host vi which send a command to a specific custom device.

- Second : a template of an asynchronous custom device under NI Versitand 2011.

It seems to be real dynamic event mechanism.

I succeed with the host vi, sending an event to my specific custom device but I don't succeed the opposite data transfer.

[Norbert_B]

Since i dont have VeriStand on my machine, i cannot look into those VIs. But i am confident, that the "Send Device MSG" VI on your host is sending a TCP command. Nothing more. It is possible, that VeriStand looks for those messages "event based" and that it will pass on that message using custom events on the target. But the host is not directly creating that event!

If there is no predefined way in the other direction, you have to implement it on your own....

Norbert

[R.Kaszubiak]

Thanks a lot for your answers.