Experimental Physics and
Industrial Control System

Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> · Thu, 18 Feb 2021 12:39:39 +0000

> the reason I ask is I have an IOC running on one machine and I have been able to access it just fine from 192.168.1.X to its IP 192.168.2.X
> but now I am trying to run the IOC on the .1 machine and the .2 access and it cant find it for some reason.

> I have checked my environment variables on both machines and I was at the time using EPICS_CA_ADDR_LIST to include each others IPs.

I believe the following is true, but EPICS experts may correct me.

Was the .1 machine running more than one IOC?  If so, then this could be the problem.  Using the IP address of the .1 machine in the EPICS_CA_ADDR_LIST on .2 will only work for the first IOC started on .1.  It will not be able to find the second IOC.  This is because the second IOC needs to use a different port for Channel Access.

However, if you set the EPICS_CA_ADDR_LIST on .2 to the broadcast address of .1 it can work.  However, it depends on the configuration.  Does .2 have 2 NICs so that it is directly connected to both the .1 and .2 subnets?  If yes, then it should work with no configuration changes.  However, if .2 is separated from .1 by a router then that router needs to be configured to allow "directed broadcasts" from the .2 subnet to the .1 subnet.

Mark

________________________________
From: Manoussakis, Adamandios <manoussakis1 at llnl.gov>
Sent: Thursday, February 18, 2021 12:34 AM
To: Manoussakis, Adamandios; Mark Rivers
Cc: tech-talk at aps.anl.gov
Subject: RE: Identical Process Variable names on Multiple Servers

I did find my answer to question

1) in the channel access pdf

EPICS_CA_ADDR_LIST="1.2.3.255 8.9.10.255"

For 3)
the reason I ask is I have an IOC running on one machine and I have been able to access it just fine from 192.168.1.X to its IP 192.168.2.X but now I am trying to run the IOC on the .1 machine and the .2 access and it cant find it for some reason.  I have checked my environment variables on both machines and I was at the time using EPICS_CA_ADDR_LIST to include each others IPs.

-----Original Message-----
From: Tech-talk <tech-talk-bounces at aps.anl.gov> On Behalf Of Manoussakis, Adamandios via Tech-talk
Sent: Wednesday, February 17, 2021 9:31 PM
To: Mark Rivers <rivers at cars.uchicago.edu>
Cc: tech-talk at aps.anl.gov
Subject: RE: Identical Process Variable names on Multiple Servers

Thanks Mark, I will try that out.  I think I tried doing it before and I wasn’t having much success with the broadcast address but I understand a bit more about EPICs not so I can hopefully debug if its something else.

This does lead me three other questions though

1) If I have multiple addresses I need to list in EPICS_CA_ADDR_LIST

Is the proper way EPICS_CA_ADDR_LIST=[192.168.1.255 192.168.2.255]?

2) I am wondering if I have multiple IOCs running on my linux machine do I need to then start to worry about starting up the CARepeater if I use the broadcast addressing?

3) If I have multiple subnets such as above 192.168.1.x and 192.168.2.x, will I run into issues if I don’t setup cagateways or am I misunderstanding there use?

Thanks,
Adam

-----Original Message-----
From: Mark Rivers <rivers at cars.uchicago.edu>
Sent: Wednesday, February 17, 2021 6:17 PM
To: Manoussakis, Adamandios <manoussakis1 at llnl.gov>
Cc: tech-talk at aps.anl.gov
Subject: Re: Identical Process Variable names on Multiple Servers

It is because you have more than one network interface and you are running the IOC and client on the same machine.

You can set EPICS_CA_AUTO_ADDR_LIST=NO and EPICS_CA_ADDR_LIST to the broadcast address of one of the interfaces.

Mark

Sent from my iPhone

On Feb 17, 2021, at 8:00 PM, Manoussakis, Adamandios via Tech-talk <tech-talk at aps.anl.gov> wrote:

Hey All,

Having a weird issue where I try to run a very simple IOC with a few analog out records and getting CA.Client.Exception
Warning: Identiical Process variable names on multiple servers
Context: Channel calc:a connecting to ubuntu:5064 ignored: localhost:5064

Ubuntu is my hostname on this VM and this is the first time I have encountered this when just running a single IOC.

Thanks

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System