Re: same PV on multiple IOC's - side effect

[Andrew Johnson <anj@aps.anl.gov>]

Hi Heinrich,

Heinrich du Toit wrote:
> I have 2 network cards in my PC - this is to connect directly to both
> the campus and the control network here at iThemba LABS.
>
> Now I have eth0 and eth1
>
> If I start an IOC and then look for a PV then both interfaces seem to
> return then I get error, although this is the same IOC?

Do you ever expect to have any IOCs on the campus network at all?  If 
not, the solution is to configure the CA client library to send CA 
searches only to the control network.  It is not possible with the 
current code to tell the IOC server to only export its PVs to a 
particular network on a machine with multiple interfaces, but as long as 
the clients only search one network they won't see the problem (for the 
purposes of the above explanation, the IOC is a client as well as a server).

To tell the client library to only search the control network, set the 
following two environment variables
  EPICS_CA_AUTO_ADDR_LIST=NO
  EPICS_CA_ADDR_LIST=<broadcast address of control subnet>
The broadcast address is shown on the output from /sbin/ifconfig -a and 
is probably 172.16.4.255 but it may have different numbers in the 3rd or 
4th positions.

As long as those variables are set before you start the IOC and/or any 
other clients you shouldn't see the duplicate PV warning.

- Andrew
--
When a distinguished but elderly scientist states that something is
possible, he is almost certainly right.  When he states that something
is impossible, he is very probably wrong.  -- Arthur C. Clarke