@atmark Can you check which version of the thermocouple daughter boards you have? The older boards are MAX31855-based, the newer ones are MAX31856-based. This will change the M305 assignment. As it says https://duet3d.dozuki.com/Wiki/Connecting_thermocouples#Section_Duet_2_WiFi_Ethernet_and_Maestro
If your daughter board uses MAX31855 chips then the terminal blocks labelled 1 and 2 on the lower daughter board will be temperature measurement channels 100 and 101 respectively. If you stack two daughter boards, the terminal blocks on the upper board will be channels 102 and 103.
If your daughter board has two LEDs labelled FAULT then it uses MAX31856 chips. In this case the terminal blocks labelled 1 and 2 on the lower daughter board will be temperature measurement channels 150 and 151 respectively. If you stack two daughter boards, the terminal blocks on the upper board will be channels 152 and 153.
If you've got newer boards, and your config.g should be set up as:
M305 P1 X150
M305 P2 X151
M305 P3 X152
Though I did test this (I only have a PT100 daughterboard and a newer thermocouple board stacked on top), using X101 did report 2000C temps. So I'm not quite sure what's going on with your setup.
Lastly, make sure there is a comment mark ; before "Super Volcano 80W 24V" in your config.g. This should be ignored, but just in case it's causing problems, put it in.
Ian
