Experimental Physics and
Industrial Control System

Ben Franksen <[email protected]> · Fri, 30 May 2008 18:27:09 +0200

On Freitag, 30. Mai 2008, Mathias Steiner wrote:
> All would be well if it were possible to change links -- either .FLNK or
> .OUT -- from within a subroutine.  I've tried a couple of things without
> success.  Just pasting the channel name into the "value" field of the
> union does not, and probably should not, work.
>
> Assigning a different value to a link by copying an input link doesn't
> work either:
> psub->flnk = psub->inpb;
>
> This isn't so clear to me, since they are both of type DBLINK.  After
> all, I can "just" type the value into the .FLNK field of any channel
> using edm, and it'll work...

It works because this operation is going via Channel Access.

You can do the same from your subroutine: use the CA client library to 
establish a channel to the FLNK (or whatever other link) field, then do a 
ca_put with the new value. A very simple example for how to use CA (client) 
is provides as a makeBaseApp template, just do

  makeBaseApp.pl -t caClient

and look at caExample.c.

I am not sure whether the ca_context_create() call is necessary if you call 
CA from a subroutine record, maybe the context has already been 
initialized?

Cheers
Ben

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System