Null Modem Cable with USB Serial Adapter

WINDBG
1

Hi,

I don’t seem to be able to set up a connection with the target from my
laptop using a USB to serial cable adapter.
My laptop doesn’t have any serial ports, so I’m using this adapter,
which creates a COM port Windbg seems happy to connect to.
I’ve run Hyperterminal on both machines, and using the baudrate and com
port settings I’m using to try and debug, I get typing coming from the
target machine, but nothing appears on the target machine sent from the
host.
Does there have to be typing going both ways ? Is there anything else I
can try ?
I’ve used the same serial cable to debug on other, all serial, set-ups.
Any ideas ?

Thanks,

Sarah F.

2

The connection must be bidirectional. If you cannot see typing going in
both directions, it will not work.

Many laptops have IEEE1394 / Firewire ports. Check and see if yours does,
and if so, try using IEEE1394 debugging instead. It is more reliable and
much faster.

– arlie

From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Sarah Fenton
Sent: Thursday, December 08, 2005 1:31 PM
To: Kernel Debugging Interest List
Subject: [windbg] Null Modem Cable with USB Serial Adapter

Hi,

I don’t seem to be able to set up a connection with the target from my
laptop using a USB to serial cable adapter.
My laptop doesn’t have any serial ports, so I’m using this adapter, which
creates a COM port Windbg seems happy to connect to.
I’ve run Hyperterminal on both machines, and using the baudrate and com port
settings I’m using to try and debug, I get typing coming from the target
machine, but nothing appears on the target machine sent from the host.
Does there have to be typing going both ways ? Is there anything else I can
try ?
I’ve used the same serial cable to debug on other, all serial, set-ups.
Any ideas ?

Thanks,

Sarah F.

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3

Given you have all the basics’ taken care of such as a NULL modem cable
jumped properly and same baud rates on both ends, USB to serial conversion
is not recommended. I have tried it several times with little success even
after dropping the bps down to 9600 or slower. Even if you do get it to
work, it is highly unreliable. Your best bet is to use 1394, or acquire a
PCMCIA serial card such as Socket.com offers.

Gary G. Little

From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of xxxxx@sarah-f.com
Sent: Thursday, December 08, 2005 12:31 PM
To: Kernel Debugging Interest List
Subject: [windbg] Null Modem Cable with USB Serial Adapter

Hi,

I don’t seem to be able to set up a connection with the target from my
laptop using a USB to serial cable adapter.
My laptop doesn’t have any serial ports, so I’m using this adapter, which
creates a COM port Windbg seems happy to connect to.
I’ve run Hyperterminal on both machines, and using the baudrate and com
port settings I’m using to try and debug, I get typing coming from the
target machine, but nothing appears on the target machine sent from the
host.
Does there have to be typing going both ways ? Is there anything else I
can try ?
I’ve used the same serial cable to debug on other, all serial, set-ups.
Any ideas ?

Thanks,

Sarah F.

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To unsubscribe send a blank email to xxxxx@lists.osr.com

4

Well, everyone seems to have different experiences with connecting, so
here’s mine.

I’ve been using a USB serial port with WINDBG for quite some time and
actually it works better that firewire. (I need to get a TI fw card for the
target, which is why…). With this set up I’ve never failed to connect at
115200.

Since you will be needing to connect to w2k, which requires a serial port
you might as well go ahead and see if you can get it to work. Plus if you
need to go out on the test floor, chances are the box won’t have a FW card.

  • Don’t put the serial port on a hub. This does not seem to work. I think
    that laptops don’t send enough power to the hub.

  • I did not have good results using a serial port that was part of a multi
    device USB dongle (those that have a serial port lpt lan etc), the one I am
    using if from Radio Shack ('cause I picked it up on the road) and is a stand
    alone device. I have used this to connect to many boxes from my laptop never
    had a problem. Also note that this serial dongle came with it’s own device
    driver, so maybe they did some thing in the driver to make it work better.
    It’s 39.00 from radio shack - not very glamorous, but cheap, available and
    for me effective.

I also use a Belkin F3B207-10 “Direct Cable Connect” which I got at compusa.
This elminates adaptors and gender benders.

You do need to get hyper terminal talking in both directions. If this won’t
work, then something is defective. It may be flow control is not right.

“Sarah Fenton” wrote in message news:xxxxx@windbg…
Hi,

I don’t seem to be able to set up a connection with the target from my
laptop using a USB to serial cable adapter.
My laptop doesn’t have any serial ports, so I’m using this adapter, which
creates a COM port Windbg seems happy to connect to.
I’ve run Hyperterminal on both machines, and using the baudrate and com port
settings I’m using to try and debug, I get typing coming from the target
machine, but nothing appears on the target machine sent from the host.
Does there have to be typing going both ways ? Is there anything else I can
try ?
I’ve used the same serial cable to debug on other, all serial, set-ups.
Any ideas ?

Thanks,

Sarah F.

5

On the other hand, I have multiple target machines hooked up to a debug
machine through a multi-port serial adapter, and it works very well. I
use the keyspan 4 port adapter; it’s capable of much higher speeds (up
to 921600 baud, which I’ve seen work keyspan-to-keyspan) than the serial
port on the target machine appears to be able to sustain. I really wish
I could use those speeds.

I have had not-so-positive results with some other brands of adapters
(no-name 3rd party; IOGear has worked for a single adapter in the past).
But for me, this keyspan has been flawless.

…dave

From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of
xxxxx@seagate.com
Sent: Friday, December 09, 2005 10:45 AM
To: Kernel Debugging Interest List
Subject: RE: [windbg] Null Modem Cable with USB Serial Adapter

Given you have all the basics’ taken care of such as a NULL modem cable
jumped properly and same baud rates on both ends, USB to serial
conversion is not recommended. I have tried it several times with little
success even after dropping the bps down to 9600 or slower. Even if you
do get it to work, it is highly unreliable. Your best bet is to use
1394, or acquire a PCMCIA serial card such as Socket.com offers.

Gary G. Little

From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of
xxxxx@sarah-f.com
Sent: Thursday, December 08, 2005 12:31 PM
To: Kernel Debugging Interest List
Subject: [windbg] Null Modem Cable with USB Serial Adapter

Hi,

I don’t seem to be able to set up a connection with the target from my
laptop using a USB to serial cable adapter.
My laptop doesn’t have any serial ports, so I’m using this adapter,
which creates a COM port Windbg seems happy to connect to.
I’ve run Hyperterminal on both machines, and using the baudrate and com
port settings I’m using to try and debug, I get typing coming from the
target machine, but nothing appears on the target machine sent from the
host.
Does there have to be typing going both ways ? Is there anything else I
can try ?
I’ve used the same serial cable to debug on other, all serial, set-ups.
Any ideas ?

Thanks,

Sarah F.

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6

What kills me is that the old ISA 16550C cards could do 921.6K for like
12.00…

Another “odd” thing - my VIA fw card works just fine sucking the data out of
my DVI cam. Like gigs of data with no errors…yet for “some” reason, winbag
barely works with it. What’s truly unfortunate about that is that since the
VIA cards seem to work flawlessly with all other drivers, that’s all you can
find in the stores.

(Hint: maybe ms should take a look at the drivers supplied with winbag, and
like get 'em to work with via cards - I’ll send ya 3 or 4 of them if you
want - I only got one camera :slight_smile:

“Sarah Fenton” wrote in message news:xxxxx@windbg…
Hi,

I don’t seem to be able to set up a connection with the target from my
laptop using a USB to serial cable adapter.
My laptop doesn’t have any serial ports, so I’m using this adapter, which
creates a COM port Windbg seems happy to connect to.
I’ve run Hyperterminal on both machines, and using the baudrate and com port
settings I’m using to try and debug, I get typing coming from the target
machine, but nothing appears on the target machine sent from the host.
Does there have to be typing going both ways ? Is there anything else I can
try ?
I’ve used the same serial cable to debug on other, all serial, set-ups.
Any ideas ?

Thanks,

Sarah F.