USB

NTDEV
1

Hello friends,
I am facing a strange problem. I have written a Application(Using
SDK calls). What this applicatin does is that it uses CREATEFILE to get a
handle to given Device Name(eg COM1). And then writes ono that device using
WRITEFILE.

My problem is When i run this Application with device name as COM1
then it runs fine. But when i run it for USB port The CREATE FILE returns an
error value of 2(means Unable to find device).

OBJDIR utility of DDK displays name of USB device as
USB#ROOT_HUB#4&2c3f8097&0#{f18a099-c30c-11d0-8815-00a00c906bed8}
And Symbolik link as USBPDO-0

What does this type of Device name mean??
I have tried all the Possible combinations of this device name in my
application.

Thanks in Advance
Navin Saini

2

> My problem is When i run this Application with device name as COM1

then it runs fine. But when i run it for USB port The CREATE FILE returns an
error value of 2(means Unable to find device).

OBJDIR utility of DDK displays name of USB device as
USB#ROOT_HUB#4&2c3f8097&0#{f18a099-c30c-11d0-8815-00a00c906bed8}
And Symbolik link as USBPDO-0

Offhand, your device can’t talk to a PDO (physical device object), it needs
to talk to a LDO (logical device object). Some driver will need to create
an LDO when notified of the device arrival. The PnP string identifying the
device will determine which driver gets to create a LDO layered above the PDO.

  • Jan
3

Hello Jan,
Can you please elaborate!!!

Who creates LDO & when. Where can i see the LDO listing

Navin Saini

From: Jan Bottorff[SMTP:xxxxx@pmatrix.com]
Reply To: NT Developers Interest List
Sent: Saturday, July 29, 2000 3:07 PM
To: NT Developers Interest List
Subject: [ntdev] Re: USB

> My problem is When i run this Application with device name as COM1
>then it runs fine. But when i run it for USB port The CREATE FILE returns
an
>error value of 2(means Unable to find device).
>
> OBJDIR utility of DDK displays name of USB device as
>USB#ROOT_HUB#4&2c3f8097&0#{f18a099-c30c-11d0-8815-00a00c906bed8}
>And Symbolik link as USBPDO-0

Offhand, your device can’t talk to a PDO (physical device object), it
needs
to talk to a LDO (logical device object). Some driver will need to create
an LDO when notified of the device arrival. The PnP string identifying the
device will determine which driver gets to create a LDO layered above the
PDO.

  • Jan

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