M408 reasonable frequency
Question most likely to @dc42 - I'm on finishing touches with my control panel. I'm "querying" the Duet with, what I think is save 5 times/s. I'm not sure what is the impact of handling the M408 S0 on the Duet and what is the max/reasonable frequency.
PanelDue polls once a second, although I may increase that to twice per second. The main overhead is probably from all the UART interrupts.