Experimental Physics and
Industrial Control System

"Peregrine M. McGehee" <[email protected]> · Fri, 20 Dec 2002 20:19:09 -0700

Russell,

We have seen a similar problem where all network access on the IOC
hangs up when a port originally used by the tnetDrv is disconnected
by external users.

In the original discussion the feedback indicated that it may be
due to the old version (v5.1.1) of vxWorks that we are running - since
at least one other site (UKIRT) had ports frequently logged out
but did not experience our problem.

We have considered, but not yet implemented, changes to the driver
to deal with this.

- Peregrine

"Redman, Russell O." wrote:
> 
> For the most part, EPICS does a pretty good job of handling non-existent
> hardware, through judicious use of the SIOL and SDIS fields.  I have just
> encountered a gap in the system.  I will be using tnetDev to talk to a suite
> of controllers through a terminal server.  I will not have the actual
> controllers for another 8 months, but am developing the necessary parts of
> the database now so I will be ready when they arrive.  I am looking for a
> way to create dummy pseudo-terminal devices similar to those created by
> tnetDevCreate, but without the need for a real terminal server on the
> network.
> 
> The tnetDevCreate routine creates pseudo-terminal devices for the ports on
> the terminal server.  This routine must run before iocInit, i.e. before any
> of the simulation mode or disabling tools of EPICS is available. When
> tnetDevCreate runs the terminal server port must exist and be configured
> correctly or really bad things happen.  My startup code looks like:
> 
>    # Start serial drivers for terminal server
>    hostAdd "harpts", "192.168.3.41"
>    tnetDevCreate "/pty/0.", "harpts", 3003
>    tnetDevCreate "/pty/1.", "harpts", 3004
>    #tnetDevCreate "/pty/2.", "harpts", 3005
>    #tnetDevCreate "/pty/3.", "harpts", 3005
>    #tnetDevCreate "/pty/4.", "harpts", 3008
> 
> If I uncomment the last three lines (attempting to access ports that have
> already been allocated by another task) tnetDev quite properly refuses to
> make the connection, but seems to hang all network access for several
> seconds.  During this period, channel access attempts to start the
> CA_repeater, CA_TCP and CA_UDP, all of which fail because they cannot create
> new sockets, and any attempt to read files using netDrv also fails.  This
> leaves me with a catch-22: if I comment out the last three lines, the
> database fails to load because "/pty/2.", "/pty/3." and "/pty/4." do not
> exist, while if I uncomment the lines iocInit fails to create necessary
> sockets and fails to read my initialization files.  There does not seem to
> be a way to make dummy devices.
> 
> In the short term I can probably fix this by adding another terminal server
> to the system, but my real concern is for the longer term when we will want
> to run the database in a pure simulation mode with NO external hardware.  It
> currently looks like we will need to plug in a spare terminal server to
> allow tnetDevCreate to complete successfully, even though the database will
> never use the devices in simulation mode.
> 
> Has anyone else encountered this kind of problem, and are there any clean
> solutions?
> 
> Dr. Russell O. Redman
> Tel: (250) 363-6917 | Fax: (250) 363-0045
> <mailto:[email protected]>
> National Research Council Canada | Conseil national de recherches Canada
> 5071 West Saanich Road           | 5071 West Saanich Road
> Victoria, B. C. V9E 2E7          | Victoria, C.-B. V9E 2E7
> Government of Canada             | Gouvernement du Canada

-- 
Peregrine M. McGehee   
Sloan Digital Sky Survey
Los Alamos National Laboratory, Los Alamos, NM 87545

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System