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'[EE]: KVM troubles.'
2003\08\20@173807 by

picon face
Hi all.
Just a quick check to see if anyone out there
have had the same kind of troubles with
a KVM (Keyboard-Video-Mouse) switch as I'm having
right now.

Scenario :
- One 4 port KVM switch (electronic, budget model, "LinkCel PS-104").
- One Compaq Armada M700 laptop computer running Win2000.
- One "noname" fairly standard minitower P-III PC running Win2000.
- A common keyboard and mouse (Microsoft original).
- One Samtron 17" LCD screen.

Now, the standard PC works just fine.

But the Compaq Laptop is having a number of different problems,
such as :

- The mouse "clicks" by itself. Different things happens
 depending on where the mouse pointer happens to be on screen.

- The keyboard double types characters in random.

- The keybaord gets into "shift lock" by itself.

- The right shift key can not be used together with the
 arrows to "select" text. (The left shift key works OK.)

- When moving the cursor by holding one of the arrow keys
 pressed, and random "4" or "6" might be "typed". The actual
 character seems to be depending on what arrow key is pressed.

Now, I have been in contact with the support dept. at the
distributor, and they says that "yes, there might be some
trouble on some laptops". They also claim the cause to be
"to low levels".

I have monitored the PS/2 lines with oscope, and the levels
are 0-5 volt on both systems. I can not "see" any other major
difference. I'v not been able to "listen" to the lines to see
if there is any difference in the character streems sent.

Well, that's more or less all.

Now, has anyone seen similar problems with KVM switches and
laptops ? And is there any reason a laptop should have
different signals on it's keybord and mouse ports ?

Jan-Erik.

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2003\08\20@201338 by john chung

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"Jan-Erik Soderholm XA (TN/PAC)" wrote:

{Quote hidden}

  I use a KVM switch at home. The last time I checked the laptop
uses the same voltage as the PC when it comes to keyboard and mouse.
PS/2. I am currently using a Aten switch which is expensive, 2port only.

 Perhaps the Compaq sent a keyboard *identification* to the KVM switch
and it did not reply correctly. That is real pain...........

>
>
> Jan-Erik.
>
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2003\08\20@202753 by Picdude

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Not sure if this is the answer, but it may help.... Is this a passive switch?  I know that Win2k and its relatives freak out if the keyboard or mouse is removed and then reconnected during operation, so passive switches are a no-no.  An "active" switch will hold the lines on the disconnected system such that the computer thinks they're still connected, though no movement/key signals are possible.  So perhaps some corrupt signal during the transistion/switch is freaking out the machine?

Cheers,
-Neil.



On Wednesday 20 August 2003 16:37, Jan-Erik Soderholm XA (TN/PAC) scribbled:
{Quote hidden}

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2003\08\21@040932 by

picon face
It's an electronic switch. All computers can boot without
problems no matter what computer is "selected" in the switch.

You switch by pressing "Scroll Lock" until the KVM switch beeps, then
press keys "1" ro "4" on the numeric keypad to select active computer.

One other thing, since the Compaq Armada only has one PS/2 connector,
I use an adapter thet converts from USB to two PS/2 connectors.
I'll do some more testing using this adapter but bypassing the
KVM switch and we'll see. I might also be able to get my hands
on a docking station for the Armada which has two PS/2 connectors
builtin (not using the USB dongle), that might also be *the* answer...

Jan-Erik.

{Original Message removed}

2003\08\21@050336 by Nigel Orr

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> One other thing, since the Compaq Armada only has one PS/2 connector,
> I use an adapter thet converts from USB to two PS/2 connectors.

One of our products uses an SBC which has only one PS/2 port (it normally
lives in a box with only a touchscreen interface, so the PS/2 port is only
needed for development).  It is supplied with a 'breakout' lead which has
one PS/2 plug and two PS/2 sockets (for keyboard and mouse).

I'm not sure how that works, but it does work!  Are PS/2 devices
interchangable if the BIOS supports it?  I had previously assumed that the
socket had to be either dedicated 'mouse PS/2' or 'keyboard PS/2'.

Anyway, you might be able to buy the breakout leads from some of the usual
electronics suppliers, it would probably be a safer bet than adding a USB
layer to the problem :-)

Nigel
--
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Axon Instruments Ltd., Wardes Road,Inverurie,Aberdeenshire,UK,AB51 3TT
              Tel:+44 1467 622332 Fax:+44 1467 625235
                  http://www.axoninstruments.co.uk

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2003\08\21@051410 by

picon face
Hi.
Yes, I'v been thinking on that also.
I'll look for a PS/2 split-cable.
Thanks
Jan-Erik.

Nigel Orr wrote:

> Anyway, you might be able to buy the breakout leads from some of the usual
> electronics suppliers, it would probably be a safer bet than adding a USB
> layer to the problem :-)

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2003\08\21@072256 by

picon face
Does anyone have a schematic for a "Y-cable" or
"cable-splitter" to connect both keyboard and mouse to
a single PS/2 port ?
Jan-Erik.

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2003\08\21@091251 by Mike Hord

picon face
>Yes, I'v been thinking on that also.
>I'll look for a PS/2 split-cable.
>Thanks
>Jan-Erik.
>
I don't know if that's going to help too much either.  My HP laptop usually
fails to pick up the mouse when I connect it through my active KVM.  Only
solution is to use a 2nd mouse through its USB connection.

Good luck!

Mike H.

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2003\08\21@092802 by

picon face
My laptop has no problem at all picking up
the mouse or keyboard. No matter which channel
is selected on the switch. It's later the problems
begins. And it's mainly the keyboard that is the
trouble.

I have now connected my keyboard and mouse directly
to the USB -> PS/2 converter on the laptop (bypassing
the KVM switch), and so far so good, it seems as there
are fewer problems.

I have also called the distributor of the switch in
Sweden and the message was "Yes, we know..." :-)
According to them, most KVM switches has problems
with laptops, it had something to do with the laptops
not beeing able to source enugh current on the 5V pin
in the PS/2 connector. Well, what do I know...

Still, I'm going to test the switch with a passive
Y-cable (split-cable) instead of the USB -> PS/2 conv.

Thanks all.
Jan-Erik.


Mike Hord [.....gaidinmdKILLspamspam@spam@HOTMAIL.COM]
> I don't know if that's going to help too much either.  My HP laptop usually
> fails to pick up the mouse when I connect it through my active KVM.  Only
> solution is to use a 2nd mouse through its USB connection.

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2003\08\21@094306 by M. Adam Davis

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mudlist.eorbit.net/~adam/pickey/connect.html
Is a page that has the schematic and pinout of a typical laptop type
splitter.

However, mine doesn't label the keyboard or mouse on the splitter,
leading me to believe that the interface chip queries the devices and
determines which one it is based on the responses.  Having a brief look
at the two different (but similar) protocols I believe this would be
easy to do without damage.

Good luck!

-Adam

Jan-Erik Soderholm XA (TN/PAC) wrote:

{Quote hidden}

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2003\08\21@094928 by Nigel Orr

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pic microcontroller discussion list <> wrote on :

> My laptop has no problem at all picking up
> the mouse or keyboard. No matter which channel
> is selected on the switch. It's later the problems
> begins. And it's mainly the keyboard that is the
> trouble.

One other idea, which may not be suitable for your application- have you
looked at RealVNC- http://www.realvnc.com/

I use it regularly when I need multiple computers on my desk, they
effectively share the keyboard, mouse and monitor of one machine, they all
need to be networked somehow (ideally ethernet), but the installation is
_amazingly_ simple, and it works very well.  And there's no need for an
extra switch box, just switch to a different viewer.

There are a variety of clients and servers available, you need a server on
each machine and a client on the machine with the keyboard, mouse and
screen.

Highly recommended, if you can use it instead.

Nigel
--
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Axon Instruments Ltd., Wardes Road,Inverurie,Aberdeenshire,UK,AB51 3TT
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2003\08\21@095148 by Keith L. Kovala

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Sorry, haven't been following this thread until now.

I use a KVM with a desktop/laptop at work.  And yes, the laptop also
only has one PS/2 port.  The Y-connectors come in two varieties.  A
plain jane (the cheaper one) model that simply takes the two connections
and sends it to the one port.  The other is a specific keyboard/mouse
splitter Y, and this is more expensive.  I wish I had known the
difference when I bought mine.  I ended up with the simple splitter.
What is happening is that with the simple splitter the computer is
sending signals to the PS/2 port and both the keyboard and mouse are
picking up these signals resulting in erradic behavior.  Two solutions,
buy a the laptop specific splitter ($20 US IIRC), or bypass the mouse on
the KVM for the laptop and plug a second mouse into one half of the Y
splitter that goes into the laptop.  That's what I did.  So now to
switch machines I tap scroll lock twice and move from one trackball to
the other... small inconvienence on the second mouse... but hey, it
works.  GRiN

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.....klkKILLspamspam.....ksu.edu


On Thu, 2003-08-21 at 08:26, Jan-Erik Soderholm XA (TN/PAC) wrote:
{Quote hidden}

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2003\08\21@100422 by

picon face
M. Adam Davis wrote:
> mudlist.eorbit.net/~adam/pickey/connect.html
> Is a page that has the schematic and pinout of a typical laptop type
> splitter.

Perfect !

I'v also found a spec for the PS/2 port on my laptop.
It specifies both pin 1 and 2 as "Keyboard/Mouse DATA"
and pin 5 and 6 as "Keyboard/Mouse CLK". Pin 3 is GND
and pin 4 is +5v as usual.

So it looks as it doesn't matter what pins are kb vs. mouse.

Jan-Erik.

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2003\08\21@204250 by john chung

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"Jan-Erik Soderholm XA (TN/PAC)" wrote:

> My laptop has no problem at all picking up
> the mouse or keyboard. No matter which channel
> is selected on the switch. It's later the problems
> begins. And it's mainly the keyboard that is the
> trouble.
>
> I have now connected my keyboard and mouse directly
> to the USB -> PS/2 converter on the laptop (bypassing
> the KVM switch), and so far so good, it seems as there
> are fewer problems.
>
> I have also called the distributor of the switch in
> Sweden and the message was "Yes, we know..." :-)
> According to them, most KVM switches has problems
> with laptops, it had something to do with the laptops
> not beeing able to source enugh current on the 5V pin
> in the PS/2 connector. Well, what do I know...
>

Okay, the passive PS/2 KVM does need a *more* current then
active KVM.

passive kvm - draws power from the PC.
active kvm - has it's own power supply.


{Quote hidden}

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2003\08\22@091527 by John Ferrell

face picon face
I use VNC on a regular basis with no problems. It is a freeby from AT&T.
It gets a bit annoying when both machines are not at the same screen
resolution.
It is slow with less than a 100 mbit ethernet.

It is not as good as my Belkin KVM, but that requires the machines to be
close together.

The remote connection in XP Pro seems to be as good as a KVM in performance.

John Ferrell
6241 Phillippi Rd
Julian NC 27283
Phone: (336)685-9606
@spam@johnferrellKILLspamspamearthlink.net
Dixie Competition Products
NSRCA 479 AMA 4190  W8CCW
"My Competition is Not My Enemy"


{Original Message removed}

2003\08\22@094547 by

picon face
Hi.
Right now I'm running *with* the KVM switch but
having the UCB -> PS/2 adapter replaced with a Y-cable,
so both the keyboard and mouse ports from the KVM switch
are direct (passive) connected to the laptop's standard
PS/2 connector.

So far (a couple of hours) all works much better :-)
So this post might very well be the last one on this issue.

Jan-Erik.

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