For prototyping a large embedded system I am looking for a card rack
with a good backplane. 20 or more slots, 64 or 96 pin DIN connector or
similar, single height, maybe Eurocard-size. Preferably not Press-Fit
but we can always hand solder, of course. Most of what's available is
VME with super-wide power and ground traces but as far as I could make
out from the data sheets no full ground plane. We've got analog stuff
on most of the cards so a ground plane is important. The bottom
(solder-side) layer should be traces so we can cut some for slot ID and
analog stuff, can't use 100% internally bussed versions.

Short of laying out our own (again...), is there something with a
ground plane that can be had off-the-shelf?

People actually still make backplanes without ground planes in them? You

--
Regards, Joerg

http://www.analogconsultants.com

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:siOzh.21495$zH1.5714@newssvr29.news.prodigy.net...

For prototyping a large embedded system I am looking for a card rack
with a good backplane. 20 or more slots, 64 or 96 pin DIN connector or
similar, single height, maybe Eurocard-size. Preferably not Press-Fit
but we can always hand solder, of course. Most of what's available is
VME with super-wide power and ground traces but as far as I could make
out from the data sheets no full ground plane. We've got analog stuff
on most of the cards so a ground plane is important. The bottom
(solder-side) layer should be traces so we can cut some for slot ID and
analog stuff, can't use 100% internally bussed versions.

Short of laying out our own (again...), is there something with a
ground plane that can be had off-the-shelf?


People actually still make backplanes without ground planes in them? You
sure about that?

Try buying maybe one of the backplanes made for blade servers. Gotta be
generic stuff out there.

You can't even do controlled impedence traces without planes.

For prototyping a large embedded system I am looking for a card rack
with a good backplane. 20 or more slots, 64 or 96 pin DIN connector or
similar, single height, maybe Eurocard-size. Preferably not Press-Fit
but we can always hand solder, of course. Most of what's available is
VME with super-wide power and ground traces but as far as I could make
out from the data sheets no full ground plane. We've got analog stuff on
most of the cards so a ground plane is important. The bottom
(solder-side) layer should be traces so we can cut some for slot ID and
analog stuff, can't use 100% internally bussed versions.

Short of laying out our own (again...), is there something with a ground
plane that can be had off-the-shelf?

On Mon, 12 Feb 2007 00:13:12 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:


For prototyping a large embedded system I am looking for a card rack
with a good backplane. 20 or more slots, 64 or 96 pin DIN connector or
similar, single height, maybe Eurocard-size. Preferably not Press-Fit
but we can always hand solder, of course. Most of what's available is
VME with super-wide power and ground traces but as far as I could make
out from the data sheets no full ground plane. We've got analog stuff on
most of the cards so a ground plane is important. The bottom
(solder-side) layer should be traces so we can cut some for slot ID and
analog stuff, can't use 100% internally bussed versions.

Short of laying out our own (again...), is there something with a ground
plane that can be had off-the-shelf?


VME backplanes have ground planes, and we do all sorts of analog stuff
in VME. Never had a problem we could blame on a backplane, even using
a motley collection of ebay crates and a bazillion different customer
situations.

http://www.highlandtechnology.com/Pages/prodind2.html#VMEprod

The slot ID thing would be a challenge with 3U VME. No problem in 6U.

John Larkin wrote:

On Mon, 12 Feb 2007 00:13:12 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:


For prototyping a large embedded system I am looking for a card rack
with a good backplane. 20 or more slots, 64 or 96 pin DIN connector or
similar, single height, maybe Eurocard-size. Preferably not Press-Fit
but we can always hand solder, of course. Most of what's available is
VME with super-wide power and ground traces but as far as I could make
out from the data sheets no full ground plane. We've got analog stuff on
most of the cards so a ground plane is important. The bottom
(solder-side) layer should be traces so we can cut some for slot ID and
analog stuff, can't use 100% internally bussed versions.

Short of laying out our own (again...), is there something with a ground
plane that can be had off-the-shelf?


VME backplanes have ground planes, and we do all sorts of analog stuff
in VME. Never had a problem we could blame on a backplane, even using
a motley collection of ebay crates and a bazillion different customer
situations.


Yes, meantime I found some with planes. But all traces inside, can't
unhook some of the DIN pins without major surgery. I guess we'll roll
our own again then.

http://www.highlandtechnology.com/Pages/prodind2.html#VMEprod


Nice! Interesting that you guys tend not to use the 2nd rail.

The slot ID thing would be a challenge with 3U VME. No problem in 6U.


6U is too monstrous for this case. It's not just ID we need but also
some near-realtime signaling from the boards to a host where the usual
IRQ1 arbitration would take too long.

Question: Since you don't seem to use slot ID how do identical boards in
one rack know which position they are in? DIP switches? Or maybe they
don't have to know in your cases?

On Mon, 12 Feb 2007 17:29:22 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:


John Larkin wrote:


On Mon, 12 Feb 2007 00:13:12 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:



For prototyping a large embedded system I am looking for a card rack
with a good backplane. 20 or more slots, 64 or 96 pin DIN connector or
similar, single height, maybe Eurocard-size. Preferably not Press-Fit
but we can always hand solder, of course. Most of what's available is
VME with super-wide power and ground traces but as far as I could make
out from the data sheets no full ground plane. We've got analog stuff on
most of the cards so a ground plane is important. The bottom
(solder-side) layer should be traces so we can cut some for slot ID and
analog stuff, can't use 100% internally bussed versions.

Short of laying out our own (again...), is there something with a ground
plane that can be had off-the-shelf?


VME backplanes have ground planes, and we do all sorts of analog stuff
in VME. Never had a problem we could blame on a backplane, even using
a motley collection of ebay crates and a bazillion different customer
situations.


Yes, meantime I found some with planes. But all traces inside, can't
unhook some of the DIN pins without major surgery. I guess we'll roll
our own again then.




I wonder how many backplanes have been invented over the years. I've
done a few myself.

http://www.highlandtechnology.com/Pages/prodind2.html#VMEprod


Nice! Interesting that you guys tend not to use the 2nd rail.


The analog stuff is mostly slow, so we don't really need 32 bit
transfers. Leaves more room on the board for stuff!


The slot ID thing would be a challenge with 3U VME. No problem in 6U.


6U is too monstrous for this case. It's not just ID we need but also
some near-realtime signaling from the boards to a host where the usual
IRQ1 arbitration would take too long.


Doesn't CPCI have geographic addressing? Those backplanes are mass
produced, too.

Question: Since you don't seem to use slot ID how do identical boards in
one rack know which position they are in? DIP switches? Or maybe they
don't have to know in your cases?


Dip switches. Nobody seems to mind.

John Larkin wrote:

On Mon, 12 Feb 2007 00:13:12 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:


For prototyping a large embedded system I am looking for a card rack
with a good backplane. 20 or more slots, 64 or 96 pin DIN connector or
similar, single height, maybe Eurocard-size. Preferably not Press-Fit
but we can always hand solder, of course. Most of what's available is
VME with super-wide power and ground traces but as far as I could make
out from the data sheets no full ground plane. We've got analog stuff on
most of the cards so a ground plane is important. The bottom
(solder-side) layer should be traces so we can cut some for slot ID and
analog stuff, can't use 100% internally bussed versions.

Short of laying out our own (again...), is there something with a ground
plane that can be had off-the-shelf?


VME backplanes have ground planes, and we do all sorts of analog stuff
in VME. Never had a problem we could blame on a backplane, even using
a motley collection of ebay crates and a bazillion different customer
situations.


Yes, meantime I found some with planes. But all traces inside, can't
unhook some of the DIN pins without major surgery. I guess we'll roll
our own again then.


http://www.highlandtechnology.com/Pages/prodind2.html#VMEprod


Nice! Interesting that you guys tend not to use the 2nd rail.


The slot ID thing would be a challenge with 3U VME. No problem in 6U.


6U is too monstrous for this case. It's not just ID we need but also
some near-realtime signaling from the boards to a host where the usual
IRQ1 arbitration would take too long.

Question: Since you don't seem to use slot ID how do identical boards in
one rack know which position they are in? DIP switches? Or maybe they
don't have to know in your cases?