AnsweredAssumed Answered

VEE locks the gateway

Question asked by VRFuser on Jul 18, 1997

Environment: Workstation HP B-160L, HP-UX V10.20, VEE 4.01, Gateway HP E2050A.


We have a system in which two workstations are linked through gateway
(LAN/IEEE-488) to the Ethernet network (LAN)and some equipment.

Each one of these workstations has a VEE program that is taking measurements
continuously by means of various equipment connected to the gateway.

Separately, it works right, but we noticed that an interference was produced
when these two applications began to function at the same time.

Both applications have the same procedure to access through the LAN-HPIB
Gateway, as  follows:

1- EXECUTE LOCK INTERFACE (with the 'interface operations' object from VEE)
2.- Request a measurement from one of the equipment of the system.

3.- EXECUTE UNLOCK INTERFACE (with the 'interface operations' object from VEE)

After making several tests, we found that the way to reproduce the problem
was executing an "unlock interface" without a previous "lock interface".
When this happens, the VEE program that provokes the situation locks the
interface, and none other VEE program can access through the LAN-HPIB
gateway (any attempting of this causes an error code arises: 814).

Moreover, the VEE program that locked the gateway can access the equipment
normally, but it cannot to unlock interface, because the 'Interface
operation' object from VEE causes the error coded as 811 when trying to do
that (and none effect is noticed).

When this situation is produced, the only way we have found to solve the
problem is to kill the VEE program that locked the gateway, and here is when
things become complicated for us, since logically, we cannot kill the VEE
processes very often.

So, if it is not possible to avoid or modify the behaviour of "EXECUTE
UNLOCK" transaction we would like to know a method for recovering the state
of LAN-HPIB gateway by means of a VEE object without having to kill our
applications each time the interference arises.

I hope you could provide me some help.



Juan Carlos Martin
E-mail     :
Phone      : 34-1-3963995
Fax     : 34-1-3963912
Earth Stations Department