Experimental Physics and
Industrial Control System

[email protected] (Jeff Hill) · Mon, 19 Jul 1999 12:30:56 -0600

> 
> The National Instruments solution to an upgrade for
> the niCpu030 is the VXIpc-850,860 or 860 pentium
> based platform which are supported by vxWorks.
> The current think at SLAC is that we would prefer 
> not to change platforms if possible.

The NI VXIpc product was initially selected
for certain systems on the LEDA project. The product was 
buggy and after several weeks attempting to get
a system working the project sent all of the units back to the 
factory, and ordered the Kinetics Systems 68060 based VXI 
slot zero CPU product as replacements. 

The primary problems were:
1) Persistent random crashes in the nivxi system code under 
interrupt load
2) Our VXI interrupt service routine was run at task level, and
not at interrupt level, by the nivxi library. No equivalent
to WRS's intConect() was implemented for VXI interrupts.
3) 300-500 uS average interrupt latency, and I suspect, much 
higher peak interrupt latency.
4) NI indicated that bug fixes to the initial
product would not be attempted until the system programmer 
had finished a SCSI driver for the product.

Its possible that items (1) and (4) could have been
resolved if we were patient, but unfortunately, we had
time pressure and we were unwilling to wait. I think that
items (2) and (3) however indicate design flaws inappropriate 
in a real time CPU product, and therefore I cannot recommend 
its use on EPICS system unless NI takes steps to redesign 
their system software.

I have CC'd to NI in case they would like to comment on the 
the current state of the above issues.

Jeff

______________________________________________________
Jeffrey O. Hill           Internet     [email protected]
LANL MS H820              Voice        505 665 1831
Los Alamos NM 87545 USA   FAX          505 665 5107

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System