R: Maximum USB Bulk Transfer

PaoloC · March 7, 2001, 2:46pm

When you say in single BULK transfer do you mean in a single USB packet ?
If so the answer is 64 bytes for each pipe if the pipe is configured to hold
64 bytes.
Anyway you can submit to the usb controller driver (USBD.SYS) a buffer large
as you want; it will split your request in the correct number of USB
packets.

-----Messaggio originale-----
Da: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com]Per conto di xxxxx@scmmicro.co.in
Inviato: mercoledi 7 marzo 2001 14.26
A: NT Developers Interest List
Oggetto: [ntdev] Maximum USB Bulk Transfer

Dear Developers,

Can any one tell me the Maximum number of bytes the USB stack is capable of
transferring in a single BULK transfer ?

Is there any difference between Windows-2000 and Windows-XP in this aspect
?

Thanks and regards,

You are currently subscribed to ntdev as: xxxxx@tin.it
To unsubscribe send a blank email to leave-ntdev-$subst(‘Recip.MemberIDChar’)@lists.osr.com

You are currently subscribed to ntdev as: $subst(‘Recip.EmailAddr’)
To unsubscribe send a blank email to leave-ntdev-$subst(‘Recip.MemberIDChar’)@lists.osr.com

OSR_Community_User · March 8, 2001, 7:38am

I have found that there is a maximum size to the buffer USBD can cope with.
This seems to vary across different machines. I have one machine that works
with 8192 but not significantly more and another that will only work with
4096 and no more… There must be a restriction put on it somewhere,
supposedly by the usb controller?

Duncan

-----Original Message-----
From: Paolo Cazzola [mailto:xxxxx@tin.it]
Sent: 07 March 2001 19:43
To: NT Developers Interest List
Subject: [ntdev] R: Maximum USB Bulk Transfer