The TCP Listen.vi does not appear to detect all items on the network reliably.

[rimfire44]

I am running a dedicated network to four devices. When I run the TCP Listen.vi it does not always detect all four of the devices. Sometimes it gets all of them and in the worst case only one device.  The issue I have is in detecting whether it is the vi or if there is something screwed up with the network, or with the devices.  I'm betting on the devices, but development engineers always tell me there stuff perfect. From time to time I have a hard time believing them for some reason.

  Has anybody got any ideas how to parse out where the issue is?  I am a newbie with TCP so stupid mistakes are not only possible, but highly likely.

Thanks,

Dave

[nathand]

Can you share your code? TCP Listen does not detect devices, it just waits for an incoming connection. A listener must be created before any device attempts to connect to it, so if you're powering up or starting a bunch of devices at the same time including the one with the listener, it's possible that sometimes it doesn't start listening soon enough to catch the initial connection attempts. Also, run Wireshark to see if the remote devices are in fact sending valid attempts to establish a connection.

[rimfire44 · Accepted solution]

Nathand,

I think you have already revealed the possible source of the problem. I think I am not using this thing correctly based on your info.  I am going to go back and rewrite things and see where I get.  And thanks for the Wireshark tip. Never heard of it before.

Thanks!