ACU-RITE MILLPWR Auxiliary - Manual (Page 29)

AMI Reference Manual 26
G-code Programs
When using a G-code program that requires coolant commands, certain
outputs are configured to specific commands (M7, M8, M9). The following
rules apply while running G-code programs:
1) M7 command turns on the Aux 1 as the coolant flood relay.
2) M8 command turns on Aux 2 as the coolant mist relay.
3) M9 turns off both Auxs 1 and 2.
4) Only one output, Aux 1 or Aux 2, is permitted to be on at a time.
5) These outputs will be turned On and Off as defined in the G-code
program.
6) Auxiliary outputs 3 and 4 are not used and are always off.