Experimental Physics and
Industrial Control System

Peregrine McGehee <[email protected]> · Fri, 05 Jul 2002 15:20:18 -0600

In tracking down an apparent channel access failure, we 
discovered that the terminal server driver (tnetDrv) behaves 
badly when the addressed terminal server port is logged out.

Specifically, the combination of the default high priority
(3) of the tTnet task coupled with the lack of a timeout
argument in the following causes the IOC to lock up.

  if (select (FD_SETSIZE, &readFds, NULL, NULL, NULL) == ERROR)
        {
            logMsg ("tnetDev: ERROR--select 0x%x\n",
                getErrno, NULL, NULL, NULL, NULL, NULL);
            break;
        }

Deletion of the tTnet task restored both channel access and
telnet communications.

We will add a default timeout argument to this select call - unless
other tnetDrv users have already done so.

- Peregrine
-- 
Peregrine M. McGehee		(505) 437-6822
Sloan Digital Sky Survey	Apache Point Observatory

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System