Experimental Physics and
Industrial Control System

Ben Franksen <[email protected]> · Sun, 15 Jan 2017 03:37:22 +0100

Am 12.01.2017 um 19:04 schrieb [email protected]:
> I've had instances of both an IOC and a CAS being unable to create a
> channel access port. The servers attempt to bind to the usual channel
> access server port number, but rather than EADDRINUSE being returned
> on failure they are seeing EACCES. Looking at
> https://msdn.microsoft.com/en-us/library/windows/desktop/ms740668(v=vs.85).aspx
> suggests another application/service might have bound to the port
> already with SO_EXCLUSIVEADDRUSE and this appears to be the situation
> (the National Instruments network variables server process in this
> case). If I change things to request a dynamic port allocation after
> any bind() failure (rather than only on EADDRINUSE) as per the
> attached patch then everything works fine

This is very nasty behaviour on part of NI. The CA ports 5064 and 5065
are registered with the IANA and officially belong to Channel Access
(both UDP and TCP), see
https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.txt.

IMO you should file a complaint with NI; they should change their
default port to some unregistered port, perhaps they want to register
their protocol with IANA under another port number, but simply hijacking
an existing registered port is not acceptable.

Cheers
Ben

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System