Paul_KD7HB:
The LED shows electronic activity on the disk drive control circuit. Even the lowest level of software, the drivers, know nothing about the LED, nor do they care. So, even if you had vast experience with WIN NT software you could still not determine the LED status.Paul
That's a bit of a "strict" interpretation of what I wrote. Some thing triggers that LED in, that something is commanded by the OS, therefore if you can tell what command caused the LED to trigger, and can monitor that command you can, in effect, tell the status of the LED.
I offer as example that there is at least one app that will put an HDD "light" in your status bar, and even flash a "lock" LED of your choice on the keyboard, but I don't like having such things running on my PC.
It is therefore obvious that ON THE PC, UNDER THE OS, it is absolutely possible - it therefore should be possible to have an applet running under Windows that sends messages to a USB connected device and cause some activity to occur.
My real intent was to find out if that could be accomplished WITHOUT having software on the host machine, in a similar manner as determining the LOCK LED status.