When not sailing, I work as a software
developer, and have recently been battling similar problems with USB-to-serial adapters that worked fine on Windows XP but fail to work reliably under Windows 7. The problems come when communicating small data packets with an external device through a usb-to-serial adapter - the same situation when your GPS is communicating with a Windows 7 computer. So far I have tried Belkin, Prolific (Micro Innovations and others using Prolific chips) and FTDI. Even using the latest drivers none of them would work reliably out-of-the-box. The only device I could get to work reliably under Windows 7 was the FTDI (www.ftdichip.com
) adapter, and even with this device I had to tweak the communications
parameters to get it to work; in particular, I extended the "latency timer" from the default 16ms to 80ms, using the "advanced" tab in "port properties" in the Device Manager. FTDI allows you to adjust this property, whereas other manufactuers do not. The default value can also be set by editing the ftdiport.inf file, and changing the "16" to an "80" in the last line, below.
;HKR,,"ConfigData",1,01,00,3F,3F,10,27,88,13,C4,09 ,E2,04,71,02,38,41,9c,80,4E,C0,34,00,1A,00,0D,00,0 6,40,03,80,00,00,d0,80
HKR,,"ConfigData",1,11,00,3F,3F,10,27,00,00,88,13, 00,00,C4,09,00,00,E2,04,00,00,71,02,00,00,38,41,00 ,00,9C,80,00,00,4E,C0,00,00,34,00,00,00,1A,00,00,0 0,0D,00,00,00,06,40,00,00,03,80,00,00,00,00,00,00, D0,80,00,00
If you need help trying this, send me an email