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<== Date ==> <== Thread ==>

Subject: Re: CAJ or PV gateway problem?
From: Dirk Zimoch <dirk.zimoch@psi.ch>
To: Mark Rivers <rivers@cars.uchicago.edu>
Cc: tech-talk@aps.anl.gov
Date: Tue, 05 Jan 2010 15:08:00 +0100
Mark Rivers wrote:
Folks,
We found a problem with CAJ and the PV gateway yesterday. The problem is that CAJ "out of the box" (e.g. without changing any of the default properties) will connect fine to PVs on the local subnet if they are contained in a VME IOC or soft IOC. But CAJ will not connect to PVs that are present in a PV gateway on the local subnet.
We've figured out the problem, and it is easy to reproduce even with traditional CA from EPICS base. The problem is that CAJ defaults to a broadcast address of 255.255.255.255 when searching for PVs. VME IOCs and soft IOCs respond to such a broadcast, but the PV gateway does not.

Hi Mark,


The EPICS default, according to the CA Reference Manual, is to use the broadcast addresses of all network interfaces. (If this makes sense or not is another issue -- imagine an IOC and a CA client on the same computer with two network interfaces => duplicate channels.)
This behavior can be modified with the environment variables EPICS_CA_ADDR_LIST and EPICS_CA_AUTO_ADDR_LIST.


The CA gateway parses its command line parameters for server and client address and modifies the environment variables before starting the CA server part. Normally, one specifies the broadcast address of one network card as the server address. Thus, I would say the gateway is working correctly.

If CAJ uses an other default and/or does not look at the environment variables, CAJ does not conform to the CA Reference Manual. I dare to say it is buggy. (And don't tell me "Java cannot read the environment" -- all Java fans say "Java can everything" :-P )

I wonder why you get any reply at all using 255.255.255.255? Is there any "magic" in the IOC server that allows IOCs to respond to 255.255.255.255 and that is not included in the portable CA server?

Dirk
Replies:
RE: CAJ or PV gateway problem? Mark Rivers
RE: CAJ or PV gateway problem? Jeff Hill

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