Callback Stats & RS485 Timeout - Significance?

[alistairts]

What is the significance of knowing the callback stats and the RS485 timeout?
What should these entities be under normal circumstances, and what should one do if they differ?
I have trended both with my callback stats ranging from 60 up to 100, and my timeouts incrementing occasionally once every 5min, sometimes once every 30min - 4hrs...