Experimental Physics and
Industrial Control System

Mark Rivers <[email protected]> · Fri, 22 May 1998 11:13:39 -0500

Hi,

>   At Jefferson Lab there are several MVME 167/177 IOCs with OMS VME44
> stepper motor control cards. When they are combined with an MVME 162
> card running HiDEOS in the same crate, we have been experiencing ioc
> crashes.  These may occur after several motor moves, or they may never
> occur, depending on the particular combination of software applications,
> OMS card and stepper motor chassis, the latter being used to supply
> power to the motor and to microstep.  When the ioc crashes, it locks
> up immediately after a step is given, and there is no way to log on to
> determine the problem.

We had VERY similar problems here at CARS on an APS beamline.  We could cause
the system to crash within < 1 minute by causing lots of Hideos traffic to
occur when a motor was moving.  Our situation was different from yours as
follows:
    - We are using OMS VME58 rather than VME44
    - We are using the "motor" record and its device support, rather than the
      "steppermotor" record and its device support.  However, the motor record
      device support has its origins in the steppermotor device support, so they
      are quite similar.

Joe Sullivan found that the problem was that OMS interrupts which were
supposed to be masked off were occasionally getting "unmasked" and occuring
anyways.  My recollection is that his solution was to "remask" these
interrupts in the interrupt service routine each time it was called.  This has
completely fixed the problem.  It is not clear if this is an OMS hardware
problem, a Hideos software problem, or software problem in the OMS driver.  
There have been a number of bugs found and fixed in Hideos recently, so the
"kluge" fix to the OMS driver may no longer be necessary.

                                Mark Rivers

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System