OSDP provides the following benefits:
OSDP is digital and bidirectional, which facilitates diagnosing communication and/or alarm problems when devices aren't responding.
OSDP is encrypted, whereas the Wiegand interface isn't and can be easily hacked.
OSDP works on only 2 wires, whereas the Wiegand interface requires up to 6 wires.
OSDP can run on a cable distance of approx. 1.2Km between the field devices, whereas the Wiegand interface only supports distances up to 150m.