KVM switch doesn't pass PnP properties

  • Thread starter Thread starter rob2xx2
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rob2xx2

I am using a Belkin Switch2 KVM switch to share an Acer wide screen monitor
between a laptop running Vista Business and a desktop running XP SP3. The
problem is that the desktop does not recognise the properties of the monitor
so the screen resolution is not ideal. The res I want is 1440x900 but this
does not appear in the list of possible resolutions. I have the most
up-to-date drivers for the graphics card (Nvidia GeForce4 MX 440 with AGP8X)
and the monitor but none of the possible options (default monitor, plug and
play monitor, Acer X193W) help.

If I boot up the desktop with the monitor connected directly it uses the
correct settings and gives me 1440x900 res, but this resets if, the next
time, I boot up via the switch.

Therefore I have two questions:

1. If I boot up via the switch and XP doesn't detect the PnP properties of
the monitor is there any way I can override it and force it to make other
settings available? (Bear in mind I have tried the
Desktop|Properties|Settings|Advanced and the Nvidia Control panel and the
option I want doesn't display; neither does it show when I click the "List
all modes" button).

2. If I boot up with the monitor directly connected and get the correct PnP
settings, is there any way I can make them 'sticky' so they are not reset
next time I boot up via the KVM switch?

Thanks
 
rob2xx2 said:
I am using a Belkin Switch2 KVM switch to share an Acer wide screen
monitor between a laptop running Vista Business and a desktop running
XP SP3. The problem is that the desktop does not recognise the
properties of the monitor so the screen resolution is not ideal. The
res I want is 1440x900 but this does not appear in the list of
possible resolutions. I have the most up-to-date drivers for the
graphics card (Nvidia GeForce4 MX 440 with AGP8X) and the monitor but
none of the possible options (default monitor, plug and play monitor,
Acer X193W) help.

If I boot up the desktop with the monitor connected directly it uses
the correct settings and gives me 1440x900 res, but this resets if,
the next time, I boot up via the switch.

Therefore I have two questions:

1. If I boot up via the switch and XP doesn't detect the PnP
properties of the monitor is there any way I can override it and
force it to make other settings available? (Bear in mind I have
tried the Desktop|Properties|Settings|Advanced and the Nvidia Control
panel and the option I want doesn't display; neither does it show
when I click the "List all modes" button).

2. If I boot up with the monitor directly connected and get the
correct PnP settings, is there any way I can make them 'sticky' so
they are not reset next time I boot up via the KVM switch?

Thanks
Click to expand...

I don't think so. AFAIK: This is one of those setups that insists on
seeing the monitor at boot in order to set it up, so if it's not there
things don't get set up properly. I have nVidia too but likely older
than yours so if it's not among the Advanced possibilities it's likely
somethign you'll have to put up with. Check the driver possibilities
and see if an update helps, but my feeling is it won't.
It must have to do with monitor type because it's not a problem here,
but ... I do have a smaller LCD monitor where it is a problem; thus
video card & monitor drivers are a distinct possibility.

Maybe someone else has an idea. For now, just make sure the KVM switch
is on the right one to start up, I guess.

Twayne
 
Thanks Twayne. Just to be clear though, when I say that XP boots up with the
correct res when the monitor is "connected directly" I mean: without the KVM
switch at all. I have to roll around on the floor under the desks and plug
the monitor into the back of the PC, boot up, then unplug the monitor and
plug it into the KVM switch to be able to use the switch as intended. :-(
It's not just a matter of the switch position while it boots. When I boot
via the switch, I always make sure that the switch is pointing to the desktop
before I turn on the computer, and leave it in that position until Windows
has started and all the preliminary stuff (checking for anti-vir updates, etc
etc) has finished.

However, it is my habit always to boot up the laptop before the desktop (I
use the laptop as my main machine now: newer and faster). Maybe I'll try it
the other way around and see if the same thing happens.

Regards

Rob
 
rob2xx2 said:
Thanks Twayne. Just to be clear though, when I say that XP boots up
with the correct res when the monitor is "connected directly" I mean:
without the KVM switch at all. I have to roll around on the floor
under the desks and plug the monitor into the back of the PC, boot
up, then unplug the monitor and plug it into the KVM switch to be
able to use the switch as intended. :-( It's not just a matter of
the switch position while it boots. When I boot via the switch, I
always make sure that the switch is pointing to the desktop before I
turn on the computer, and leave it in that position until Windows has
started and all the preliminary stuff (checking for anti-vir updates,
etc etc) has finished.

However, it is my habit always to boot up the laptop before the
desktop (I use the laptop as my main machine now: newer and faster).
Maybe I'll try it the other way around and see if the same thing
happens.

Regards

Rob
Click to expand...

As a user of KVMs I'd appreciate hearing back what you discover.
Imagine others would be interested too.
 
I think I have resolved this issue finally. As so often, I found the answer
when I eventually found the right terms to search Google.

I believe the root of the problem is the fact that the graphics card and
driver are Nvidia. It may not be the same for other brands. Try Googling
"native resolution Nvidia" and you'll find many discussions about getting the
correct resolutions - none of them by the way, to do with KVM switches.

It is to do with how the Nvidia driver responds to the EDID data (or lack of
it) from the monitor. First, the "List All Modes" feature does NOT list all
modes. When it booted up wrongly, the 1440x900 resolution was not present.
This is a characteristic of Nvidia drivers which only display modes which it
believes are supported by the monitor it has found. The list *is* monitor
dependent.

Second, I had been plagued by the apparent inability to enter a custom
setting using the Nvidia control panel. There is no option to do this in the
newer control panels. However if one selects the 'Classic view' (even this
choice is not blatantly obvious) the option is there. After adding the custom
res of 1440x900 to the default list, and asserting this setting, it has
indeed 'remembered' it and my desktop has booted up correctly many times over
the last couple of days. I assume it is now fixed. Of course the adapter is
still not detecting the monitor correctly, but it now has the correct res
available for it to assert.

As far as the Belkin KVM is concerned, I am guessing that for some reason
the Nvidia card/driver is not able to reliably read the EDID data from the
monitor through the switch2. Curiously, when Windows first starts and asks
for the login password the resolution seems to be correct - it's only after
this that the problem arises. I'm out of my depth here, but I guess this
means that the BIOS is able to start up a graphics driver OK. Maybe it's just
a bog-standard VGA driver or something and is such low-res that the problem
is not exhibited.

Otherwise I want to stress that I am very happy indeed with the Belkin
Switch2 KVM and the Nvidia graphics cards. The switch2 works nicely even
with my Advent wireless mouse/keyboard which has a single USB dongle plugged
into the Switch2 USB socket.

Rob
 
rob2xx2 said:
I think I have resolved this issue finally. As so often, I found
the answer when I eventually found the right terms to search Google.
Click to expand...

Ain't that the way it goes? As good as Google is, sometimes you still
almost have to be a mindreader.
I believe the root of the problem is the fact that the graphics card
and driver are Nvidia. It may not be the same for other brands.
Try Googling "native resolution Nvidia" and you'll find many
discussions about getting the correct resolutions - none of them by
the way, to do with KVM switches.

It is to do with how the Nvidia driver responds to the EDID data (or
lack of it) from the monitor. First, the "List All Modes" feature
does NOT list all modes. When it booted up wrongly, the 1440x900
resolution was not present. This is a characteristic of Nvidia
drivers which only display modes which it believes are supported by
the monitor it has found. The list *is* monitor dependent.
Click to expand...

FYI, perhaps it model dependent, but mine (an fx5200e(older model))
lists all the modes the card is capable of or alternatively only the
ones the monitor is capable of. What it doesn't do though is tell you
which list you're looking at. Near as I can tell it's accurate.
Second, I had been plagued by the apparent inability to enter a custom
setting using the Nvidia control panel. There is no option to do this
in the newer control panels. However if one selects the 'Classic
view' (even this choice is not blatantly obvious) the option is
there. After adding the custom res of 1440x900 to the default list,
and asserting this setting, it has indeed 'remembered' it and my
desktop has booted up correctly many times over the last couple of
days. I assume it is now fixed. Of course the adapter is still not
detecting the monitor correctly, but it now has the correct res
available for it to assert.
Click to expand...

Hmm, that one sent me scurrying. I can't find any way to give my own
custom res settings. With today's monitors I can see where that might
be pretty useful to have.
As far as the Belkin KVM is concerned, I am guessing that for some
reason the Nvidia card/driver is not able to reliably read the EDID
data from the monitor through the switch2. Curiously, when Windows
first starts and asks for the login password the resolution seems to
be correct - it's only after this that the problem arises. I'm out of
my depth here, but I guess this means that the BIOS is able to start
up a graphics driver OK. Maybe it's just a bog-standard VGA driver or
something and is such low-res that the problem is not exhibited.
Click to expand...

Dunno; I had a Belkin too and one of the ports, I think it was 2, had a
high resistance in its pass thru. I had no specs, but assumed 1 and 2
should have had approximately the same impedances, the specs IIRC were
something like max. 127 ohms resistive and port 2 with my
super-accurate-no-tolerance-Radio-Shack-Special showed it at around 540
ohms. It still worked, but it was slow to make the switch from one ot
the other in the monitor line; keyboard/mouse seemed to work fine.

Thanks for the "101" basics; I'm always happy to discover new things.
Oh, the Belkin gave up after a few months and I replaced it with
another - that one has worked flawlessly ever since; a couple years at
least.
nVidia seems like a good brand too; I've had 4 machines used it and
this machine has the TV out, multiple monitors, capture, etc. version,
all that good stuff - it's old but sort of an old faithful. Never had
any problems I could relate to it at least.

Cheers,

Twayne
 
"Rob":
"Twayne":
FYI, perhaps it model dependent, but mine (an fx5200e(older model))
lists all the modes the card is capable of or alternatively only the
ones the monitor is capable of. What it doesn't do though is tell you
which list you're looking at. Near as I can tell it's accurate.
Click to expand...

Rob: Interesting. Do you know how it selects which list to display? So
often 'new features' of software take control away from the user. Great for
the inexperienced user but frustrating if you want to troubleshoot. Perhaps
also, to be fair, these days the complete list of *all* possible resolutions
and refresh rates would be an exceedingly long list indeed. I got the
information that the (new) Nvidia drivers modify this list from a forum
discussion (whose link I have now lost, sorry). It seemed to be an issue with
several of the contributors who had bought large displays for gaming.

"Rob":
"Twayne"
Dunno; I had a Belkin too and one of the ports, I think it was 2, had a
high resistance in its pass thru. I had no specs, but assumed 1 and 2
should have had approximately the same impedances, the specs IIRC were
something like max. 127 ohms resistive and port 2 with my
super-accurate-no-tolerance-Radio-Shack-Special showed it at around 540
ohms. It still worked, but it was slow to make the switch from one ot
the other in the monitor line; keyboard/mouse seemed to work fine.
Click to expand...

Rob:
<smacks forehead> I had assumed that the switch would be completely
symmetrical. (It looks it from the outside :-) ). I should have tried
exchanging the cables. If I have some time after this project is over maybe
I'll delete the custom setting, get the old problem back, and do the expt.
.... or maybe I'll just leave well alone.

"Twayne"
Thanks for the "101" basics;
Click to expand...

Rob:
Oh, I wasn't trying to play teacher .. just pass on the experience.

"Twayne":
I'm always happy to discover new things.
Click to expand...

Rob:
Me too. I guess it's a substitute for a childhood spent taking clocks and
radios apart!

"Twayne":
Oh, the Belkin gave up after a few months and I replaced it with
another - that one has worked flawlessly ever since; a couple years at
least.
Click to expand...

Rob:

Want to name names?
 
rob2xx2 said:
"Rob":

Rob: Interesting. Do you know how it selects which list to display?
Click to expand...

lol, took me a minute to find it! Something switched it to the newer
view mode and I can never find anything in that! Once I got it back to
my familiar Classic Mode, I was all set!
In my case I have the left hand flyout enabled and choose Resolution
and Refresh Rate settings. On that screen there's a tick for "hide
modes this monitor can't support", or in other words, SHOW modes this
monitor can support.
So often 'new features' of software take control away from the user.
Great for the inexperienced user but frustrating if you want to
troubleshoot. Perhaps also, to be fair, these days the complete list
of *all* possible resolutions and refresh rates would be an
exceedingly long list indeed.
Click to expand...

That may be true I gues. My poor video card is maxxed out with this
monitor as far as resolution goes, but it still works fine for my needs.

I got the information that the (new)
Nvidia drivers modify this list from a forum discussion (whose link I
have now lost, sorry). It seemed to be an issue with several of the
contributors who had bought large displays for gaming.
Click to expand...

I'm not a gamer so I don't follow any of those type of groups but I do
know those guys can be pretty picky<g>. With the number of new players
over the last few years in the monitor arena though I can imagine there
are some pretty odd ones and even oddball ones out there. It must be a
lot to keep up with. I'm not that picky but I do insist on good looking
graphics so I tend to stick with branded names I know for video.
"Rob":

Rob:
<smacks forehead> I had assumed that the switch would be completely
symmetrical. (It looks it from the outside :-) ). I should have
tried exchanging the cables. If I have some time after this project
is over maybe I'll delete the custom setting, get the old problem
back, and do the expt. ... or maybe I'll just leave well alone.
Click to expand...

They're supposed to be symmetrical of course, but the "switches" are
usually only CMOS switches I discoved and they're easily "punched thru"
or otherwise damaged, but they do give the lowest "on" resistance as I
recall from my design days. Well protected from the outside world, but
still CMOS technology.
"Twayne"

Rob:
Oh, I wasn't trying to play teacher .. just pass on the experience.

"Twayne":

Rob:
Me too. I guess it's a substitute for a childhood spent taking
clocks and radios apart!

"Twayne":

Rob:

Want to name names?
Click to expand...
Oops; sorry. It was another Belkin<g>. I'm still loyal to the name.
IIRC I got them both thru CyberGuys.com.

Note: I'm no guru by any means; like you, just interested in things. I
was an electrical engineer in my past lives and lucky to have found a
field I loved working in.

Regards,

Twayne
 
rob2xx2 said:
I am using a Belkin Switch2 KVM switch to share an Acer wide screen monitor
between a laptop running Vista Business and a desktop running XP SP3. The
problem is that the desktop does not recognise the properties of the monitor
so the screen resolution is not ideal. The res I want is 1440x900 but this
does not appear in the list of possible resolutions. I have the most
up-to-date drivers for the graphics card (Nvidia GeForce4 MX 440 with AGP8X)
and the monitor but none of the possible options (default monitor, plug and
play monitor, Acer X193W) help.

If I boot up the desktop with the monitor connected directly it uses the
correct settings and gives me 1440x900 res, but this resets if, the next
time, I boot up via the switch.

Therefore I have two questions:

1. If I boot up via the switch and XP doesn't detect the PnP properties of
the monitor is there any way I can override it and force it to make other
settings available? (Bear in mind I have tried the
Desktop|Properties|Settings|Advanced and the Nvidia Control panel and the
option I want doesn't display; neither does it show when I click the "List
all modes" button).

2. If I boot up with the monitor directly connected and get the correct PnP
settings, is there any way I can make them 'sticky' so they are not reset
next time I boot up via the KVM switch?

Thanks
Click to expand...

My experiences is that when you boot a system from power off the POST
code (power on self test) in the BIOS *must* see the connection. So the
instant I push power-on hit the switch on the KVM. For many systems the
POST code determines the results (Not the operating system).
 
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