Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Tue, 24 Apr 2007 07:38:37 +0200

I was able to check this a bit further before taking off to the EPICS

meeting at DESY:

It's even worse. Not only the CA server doesn't respond to name requests

anymore, even the IOC initialization doesn't finish.

In our case, the main communication tasks for the CAN field bus are

started at the final init step. If the AS file doesn't exist, CA doesn't

find the channels anymore. When I went to the IOC, I saw there was no

CAN traffic. Checking on the IOC's console, I found these tasks were not

started.

Looks as if IOCinit bails out somewhere in the middle of doing things if

the AS file doesn't exist.

Again: I agree that not giving any access would be the correct behavior

in that case. Not finishing the IOC startup is too much of a penalty.

Cheers,
Ralph

Ralph Lange wrote:

Ned -

I thought about this, too ... and I would completely understand if the

CA server does not grant access (neither read nor write) to any

channels in that case.

But actually it doesn't even resolve the names anymore, which is a

different thing, misleading, and probably neither appropriate nor

intended.

Ralph

Ned D. Arnold wrote:

Ralph -

I think the behavior that you observed is by design ... if one tries

to specify a configuration file that does not exist, it means you

intended to have *some* access control in place. If the file doesn't

exist, this is a fatal error and the safest thing to do is not allow

any access at all so someone will fix the problem immediately.

I actually remember this discussion with Marty Kraimer about 16 years

ago ...

  Ned