I am developing some usb device on LPC2141 using CDC ACM class. Main problem is that I need to handle both XP and 2k system using usbser.sys. Almost everything works fine, enumeration, line control requests, modem status events, out transmissions, but I have problem with IN transfers on win2k. I tried 5.0.2195.6655 (sp4) and 5.0.2195.7006 (KB838417) usbser drivers and both act same way: small IN transfers (smaller than ep size) works fine. Problem occurs when I try to send larger amount of data (divided in ep size transfers + rest of data). Windows receives only first (ep size) chunk of data, but if I close and open com port again the missing data pops out. I am using modified stack (to handle LineControl and ModemStatus) based on an10420 with ZLP after ep size transmission. I tried adding ZLP after every last chunk of data, but it doesn't change anything. Does anyone know how to handle data transfers in win2k. Please help...
Best regards Krzysztof