Experimental Physics and
Industrial Control System

Richard Farnsworth <[email protected]> · Tue, 28 Sep 2010 10:11:56 +1000

Hi Jeff,

It's the PLC's broadcast traffic, i.e. network loading, not CA's use of anything that it the issue. We have been expanding the PLC networks as the facility matures. We need the multicasting for the PLC "keep alive" or heartbeat timers.

Complex, and possibly poorly described by myself, but I was just trying to emphasize your point about multicasting. It's conceptually easy to allow at the start, but down the track can causes headaches.

Cheers

Richard

-----Original Message-----
From: Jeff Hill [mailto:[email protected]]
Sent: Tuesday, 28 September 2010 9:58 AM
To: Richard Farnsworth; [email protected]
Subject: RE: Soft IOCs and Port Numbers

Hi Richard,

> At first it was tolerable, but lately, with
> increasing network traffic it's becoming a serious problem

Was this an issue with embedded system CPU loading, network
loading, or router firmware correctness issues?

It has always been my intention that CA's use of broadcasting
will been gentle with user networks. Any use of multicasting
would be scheduled using the same code base so hopefully you
wouldnât experience CPU or network loading substantially
different than current practice.

Jeff
______________________________________________________
Jeffrey O. Hill           Email        [email protected]
LANL MS H820              Voice        505 665 1831
Los Alamos NM 87545 USA   FAX          505 665 5107

Message content: TSPA

> -----Original Message-----
> From: Richard Farnsworth [mailto:[email protected]]
> Sent: Monday, September 27, 2010 5:15 PM
> To: Jeff Hill; 'Andrew Johnson'; [email protected]
> Subject: RE: Soft IOCs and Port Numbers
>
> > Nevertheless, multicasting will probably be easier to configure, and
> more importantly for your users
> > to understand, if one doesnât object to enabling multicasting in his
> control system routers. Many
> > sites already make this concession for at least some of their Allen
> Bradley PLCs, as I recall.
>
> We at the Australian Synchrotron have this latest issue alluded to by
> Jeff  - that is multicasting is enabled for our PLC's (Schneider
> Modicon Premiums). At first it was tolerable, but lately, with
> increasing network traffic it's becoming a serious problem and has
> started to affect other equipment - Most notably the timing system
> control. Our solution will involve second network cards for some PLC's
> and the separation of PLC networks.
>
> Cheers
>
> Richard Farnsworth | Head of Computing | Australian Synchrotron
>
> Please Note: From 13th October 2010 I shall be no longer employed by
> the Australian Synchrotron. If you wish to communicate personnally
> after that date please use [email protected], or wait
> for my first post with an APS email address.
>
>
> ----
>
>
> -----Original Message-----
> From: [email protected] [mailto:tech-talk-
> [email protected]] On Behalf Of Jeff Hill
> Sent: Tuesday, 28 September 2010 8:00 AM
> To: 'Andrew Johnson'; [email protected]
> Subject: RE: Soft IOCs and Port Numbers
>
> > Do you have to configure CA clients running on a
> > machine with multiple interfaces to only use one
> > of them for broadcasts, or would CA take care of
> > that for you if they're all in the same subnet?
>
> The default is for CA to broadcast on all active
> LAN interfaces it finds, and unicast on all
> active point-to-point interfaces it finds.
>
> I suppose that a new environment variable perhaps
> named EPICS_CA_SUBNET_LIST might make configuring
> broadcasts for all interfaces attached to one or
> more subnets easier.
>
> Nevertheless, multicasting will probably be easier
> to configure, and more importantly for your users
> to understand, if one doesnât object to enabling
> multicasting in his control system routers. Many
> sites already make this concession for at least some
> of their Allen Bradley PLCs, as I recall.
>
> Jeff
> ______________________________________________________
> Jeffrey O. Hill           Email        [email protected]
> LANL MS H820              Voice        505 665 1831
> Los Alamos NM 87545 USA   FAX          505 665 5107
>
> Message content: TSPA
>
>
> > -----Original Message-----
> > From: [email protected] [mailto:tech-talk-
> > [email protected]] On Behalf Of Andrew Johnson
> > Sent: Friday, September 24, 2010 11:10 AM
> > To: [email protected]
> > Subject: Re: Soft IOCs and Port Numbers
> >
> > On Friday 24 September 2010 11:24:42 Ralph Lange wrote:
> > >   On 24.09.2010 12:16, Eric Norum wrote:
> > > > Or run every IOC in it's own virtual machine?
> > >
> > > Have been investigating that- too thick. Running a VM only to have
> an
> > > additional IP address .... nah.
> > >
> > > I would prefer the solution that uses virtual network interfaces on
> > the
> > > soft IOC host. Relatively slim, completely transparent, does not
> need
> > > additional services.
> >
> > But it does require configuring a alias interface and providing an IP
> > address
> > for each soft IOC you want to run.  If you're using non-routable
> > addresses the
> > extra IPs may not be a major issue (as long as your subnets were made
> > large
> > enough), but it might mean getting IT involved every time Controls
> > wants to
> > add a new soft IOC.  Do you have to configure CA clients running on a
> > machine
> > with multiple interfaces to only use one of them for broadcasts, or
> > would CA
> > take care of that for you if they're all in the same subnet?
> >
> > A machine-specific name-server would be more efficient since each PV
> > name
> > request only has to be checked once by the name-server rather than by
> > all of
> > the IOCs on the machine.
> >
> > - Andrew
> > --
> > The best FOSS code is written to be read by other humans -- Harald
> > Welte
>
>
>
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<br>This message and any attachments may contain proprietary or confidential information. If you are not the intended recipient or you received the message in error, you must not use, copy or distribute the message. Please notify the sender immediately and destroy the original message. Thank you.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System