RE: Channel access over wireless?

[Mark Rivers <rivers@cars.uchicago.edu>]

Hi Ralph,

 

I’m confused.  You said:

 

> Setting EPICS_CA_AUTO_ADDRESS=NO suppresses the UDP broadcast

 

But what if I set

 

EPICS_CA_AUTO_ADDR_LIST=NO

EPICS_CA_ADDR_LIST = 164.54.160.255

 

I do this to restrict EPICS_CA_ADDR_LIST to the broadcast address of one of my NICs.  Don’t I still get UDP broadcasts?

 

Mark

 

From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of Ralph Lange
Sent: Thursday, October 31, 2013 1:14 PM
To: EPICS Tech-Talk
Subject: Re: Channel access over wireless?

 

On 31.10.2013 18:55, Emmanuel Mayssat wrote:

I am contemplating a project which requires wireless communication.
I would like to have telemetry information on a control station.
The network link specification is: range 1 mile at 250Kbps
Latency could definitely be an issue (measurement needed at this point)
I could potentially have several 250Kpbs links (not sure whether they can be 'trunked' together)

The remote device could run an IOC (I need something like a 'fast' sequencer for sure)
Between local OPI and remote IOC, I can use any communication protocol I want

Classic architecture:
local OPI ---- (CA over wireless) --- remote IOC
is there a way for an OPI to bypass the UDP discovery process and force connection to a specific IP addres/port?

Setting EPICS_CA_AUTO_ADDRESS=NO suppresses the UDP broadcast
Setting EPICS_CA_ADDRESS_LIST restricts discovery traffic to a list of IP/port addresses
Setting EPICS_CA_NAME_SERVERS uses TCP for discovery traffic to a list of IP/port addresses

Setting both
   EPICS_CA_AUTO_ADDRESS=NO
   EPICS_CA_NAME_SERVERS=your.destination.ip.address:port
will run Channel Access exclusively to that server/port, using TCP for name resolution and data.
You could e.g. use this to tunnel CA through SSH.

You can find more information in the Channel Access Reference Manual.

HTH,
~Ralph