To
pick up one
point that DrewE and other commenters alluded to:
The reason that newer generation fixtures aren't limited to 31 devices on a link is that newer generation *silicon* isn't: this is equivalent to the reason why it's possible to go longer distances than the original spec says on
Ethernet *on switched networks*. Before switches became ubiquitous, the distance limitations on
Ethernet had to do with being able to detect collisions, the length of the packets, the speed of light, velocity factor, and like that; if you made the
network too long, you couldn't detect collisions, and all was chaos.
Since we went to switches, that's not an issue, and simultaneously,
Ethernet PHYs got *much* more impressive; you can go half a mile on copper now, as long as you don't get too close to
fluorescent lights.
A similar thing has happened with RS-485 transceivers over time; the distance/noise issues have gotten better, as has the amount of load the receiver places on the
line. Different transmitters can be at different ends of the specification tolerance, as well...