To configure my routers I love to have a serial connection available in case I mess up the configuration. This might be in the interface, dhcp or firewall part of the setup. Once the PC is locked out, it’s pretty ugly to get back in without a serial interface.
The serial interface always works, regardless of the network setup of the box.
So at least I thought.
The RealityI had two USB to serial converters with the chipset PL-2303 XA/HXA on them. I just put the first one in the USB port, connected my some ten years old CISCO serial cable to it and plugged the jack into the router.
The connection worked right away but every now and then – sometimes after a few seconds, sometimes after minutes or hours – my Windows 7 PC crashed with a Blue Screen of Death (BSoD). This only happend, when the serial connection was in use.
To identify the exact chipset I used the tool checkChipVersion_v1006.exe which comes with the Prolific driver package.
I tried the latest drivers (1.9.0/184.108.40.2063) from the Prolific website, but this driver did not work at all since it did not detect the USB adapter. So I was stuck with the old version (1.8.19/220.127.116.112) of the drivers which regularly crashes the whole system.
After spending quite a few hours on debugging, reinstalling and so on, I came to the conclusion that the Prolific adapters are completely useless and I went for another solution.
I got myself a FTDI/FT232RL based USB adapter (Digitus DA-70156 USB Seriell Adapter) and from that moment on all my problems were gone. I plugged in the adapter, Windows 7 installed all drivers automatically and my serial connection never crashed the system again.