I'm using notebook HP nx6125 without COM port for S5 programming at work.
my configuration is:
OS - WinXP
Soft - PG2000
USB to COM converter - PL2303 chip based
RS232-TTY converter - siemens 6ES5 734-1BD20
The key problem is USB-COM converter choosing.
There are a lot chips of USB-COM converter:
PL2303 from Profilic
PL2303X from Profilic
СP2101, CP2102, CP2103 from SiliconLabs (before Signal)
TUSB3410 from TI
FT232AM, BM, BL from FTDI
KL5KUSB116 from Kawasaki
and PIC with USB port based (this kind is conceptual familiar to TUSB3410).
I have tested some of them:
FT232AM and PL2303 are working with S5 perfectly,
CP2101 and PL2303X are not working with S5.
PL2303 and PL2303X are using the same driver, so you chould chek your USB-COM converter by UVCView.x86.exe from Microsoft.
If bMaxPacketSize0 is:
64 - chip is PL2303X
8 - chip is PL2303.