NI USB-6509 Self-Test

Hello all,

Does anyone know what the built-in self-test of the NI USB-6509 hardware or any similar digitial I/O hardware does? Does it just confirm the hardware can communicate, or it actually tries to write and read certain digitial I/O lines?

I just want to have some idea about what it means when the self-test passes or fails.

Thanks,

Wenhao