Stop TCP-Read without killing the connection?

[Greil]

Hello,

is there a way to abort TCP-Read without closing the connection?

Example:

My VI (client) is connected to a device (server).

My client is waiting at "TCP Read" with timeout 10sec.

In a parallel loop I want to abort the "TCP Read" faster than 10sec but the connection must not be killed with "TCP Close Connection".

[Gregory]

Can you make the timeout shorter?

[Kyle97330]

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@Greil wrote:

Hello,

is there a way to abort TCP-Read without closing the connection?

Example:

My VI (client) is connected to a device (server).

My client is waiting at "TCP Read" with timeout 10sec.

In a parallel loop I want to abort the "TCP Read" faster than 10sec but the connection must not be killed with "TCP Close Connection".

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Make a FOR loop around the TCP read where the amount of loops it runs divides the timeout.  So instead of waiting 10 seconds 1 time, wait 1 second 10 times, or 0.1 second 100 times.  Then just add a conditional terminal to the FOR loop to allow early termination via some form of messaging, or upon receipt of the expected message, and add a "Clear error" that clears a timeout error each loop (but does not clear other error types).

[Greil · Accepted solution]

The reason why the "TCP Close Connection" is 'no option' is because the device needs always a "stop" command before closing the connection (even on error), otherwise the device needs a reset before next use. The reset takes much more time ... so this must be avoided.

(jup, it is a stupid device)

Thank You, but I found another approach:

In the parallel loop now I do TCP-Write "stop" and then it is safe to use "TCP Close Connection". This will abort the "TCP-Read" and the device will not hang up.

I could also write something else like *IDN?" so the read finished immediately too.

Thank You.

[Gregory]

That's interesting. Usually I try to avoid talking to an instrument from 2 different loops, but it sounds like you're being careful about it so hopefully it won't cause any headaches.