Rockwell's datapump interface is analog where the
proprietary is digital... Hence 2 less D/A conversion
and higher S/N ratio. Under ideal condition, yes...
not much different... Try communicate at 33.6kbps
wire speed, you will then see the differences.
Other reasons for digital interface are:
(1) Manageability (1 to 60s here in Australia)
(2) Line aggregation
(3) Eliminate extra routing stage (no router required)
(4) Dynamic bandwidth allocation
(5) Cheaper when lines > 200.