Re: Question on transition modules

["W. T. Waggoner" <bwaggoner@creighton.edu>]

This is a related question to transition modules.   I have had limited
experience with these, but have learned a great deal over the last 18 months
since joining the STAR experiment at BNL.

Hi,

One issue that came up was that we had one MV167 that was connected to an
older 712A/B modules.  We tried to replace this with a somewhat newer 712M
module (we tried two that we had tested on an identical setup).  For some
reason we couldn't get  the 712M     replacements to work in the VME crate.
We had a work around that we used during the experiment run, and will be
getting a much better look at this over the summer, but since this came up
here I thought I would pipe up.

>From what I can see, and from reading (and re reading) the manuals I cant
see where the ribbon cable connections differ nor why this didn't work.
>From the message below I am guessing its something that was done to
"homebrew" the crates.

It is not my crate and  the changes predate my contacts.  Any suggestions as
to what might cause this, and a fix would be appreciated.  Perhaps its not a
homebrew issue at all?

Bill Waggoner

bwaggoner@creighton.edu
Creighton Univ.
2500 California Plaza
Omaha NE 68178
402 280 2208
BNL
Bldg. 902 B
Upton NY 11973
631 344 7803
----- Original Message ----- 
From: "Chestnut, Ronald P." <ronc@slac.stanford.edu>
To: <tech-talk@aps.anl.gov>
Sent: Friday, June 04, 2004 5:41 PM
Subject: Question on transition modules


> In our group at SLAC we are using some MV167/MV177 and some PPC 2700 VME
controllers. Each class has its own transition module. Rumor has it that
using the wrong transition module can damage the CPU. Since there seem to be
active components on the transition module, this is entirely believable.
>
> We also have some older VME crates with homebrew "transitions"; these
crates all currently have MV167/MV177 modules. The interface is entirely
passive, with connections to the backplane and to external connectors for
one console port and ethernet. The advantage of these crates is that one can
actually get modules in without a mallet, and that many are available. The
layout of the crate precludes using the commercial 2700 transition module
without moving the power supply around.
>
> Before I fry an MV2700, I would like to know if this purely passive
"transition" solution has the possibility of actually harming the CPU. Can
anyone explain the caveats of these transition issues, please!
>
> Thank you in advance.
>
> /Ron Chestnut
>