Experimental Physics and
Industrial Control System

well said - and worth putting on tech-talk.
Bob


-----Original Message-----
From: Steven M. Hartman [mailto:[email protected]]
Sent: Wed 1/6/2010 10:41 AM
To: Dalesio, Leo; Josh Stein
Cc: EPICS tech-talk
Subject: Re: Revision tracking on vendor supplied updates?

Dalesio, Leo wrote:

> If it ain't broke - don't fix it.

Most of the time, it's not so simple. It is reasonable to assume
that most of these devices are always broken, at least a little
bit. It's a matter of deciding whether the fix (new firmware, new
software, etc) is worth the effort and risk (introducing new bugs
or exposing latent bugs) of the upgrade. Some vendors are better
about giving you the information to make this decision then others.

We are in the process of upgrading firmware on our AB PLCs. We
have identified a few cases where a bug which bit us has been
fixed in later firmware, but in other cases it is unclear from the
release notes whether the fix is really what we need. There has
been one case where the upgrade introduced a new problem
(undocumented decreased stack size) but luckily that showed itself
immediately and the change could be backed-out. But overall, the
upgraded firmware seems to be an improvement, and having
consistent levels of firmware used everywhere helps in
understanding what we have.

Josh Stein wrote:

 >   With the proliferation of small highly-distributed IOCs and
 > remote I/O we are seeing a rapid increase in the number of
 > "intelligent" devices connected to our control systems. . . .
 > Often times this firmware is not quite... as firm... as one
 > would hope

Just one of the hidden costs of highly distributed remote I/O. As
Bob said, hardware is cheap compared to labor. More protocols and
device drivers to support, more types of spares to keep track of,
more types of devices to troubleshoot, more network nodes, more
network traffic, etc.

Josh Stein wrote:

 > Finally; assuming firmware updates are an accepted price to pay
 > for COTS devices, how do we manage and track them?

The work is in deciding which devices are worth tracking and then
for those, knowing which firmware version is installed where,
which firmware version you want installed, and knowing when the
vendor releases a new version which may be better then what you
have. We are concentrating on devices which have a more direct
impact on availability (such as PLC processors and communication
modules) and dealing with other devices on a case by case basis.
Overall, not that different then dealing with software, but
potentially a lot more devices and often more difficult in getting
detailed information on the changes.


--
Steven Hartman
[email protected] || 865-466-6473

References:

Revision tracking on vendor supplied updates? Josh Stein

RE: Revision tracking on vendor supplied updates? Dalesio, Leo

Re: Revision tracking on vendor supplied updates? Steven M. Hartman

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