I found this in a microchip documentation dealing with DALI (Digital Addressable Lighting Interface) protocol. The DALI protocol is mostly used to communicate with lighting equipment. I can already understand what is going on for the most part but I'm still having trouble with the function of the diode bridge. I know that diode bridge are used to convert AC to DC voltage. But in this circuit, the input is already a DC voltage, so I'm wondering what is this diode bridge doing exactly?
While the DALI bus has DC power on it, the wiring topology is not polarity-sensitive. That is, either wire can go on either pin of any DALI interface connector. From the Wikipedia page:
"Each device has a bridge rectifier on its input so it is polarity-insensitive."