Miller Millermatic 350P Technical Manual page 63

Always perform pre-power troubleshooting before applying power to unit (see Section 8).
Receptacle
RC13
RC14
RC64
Millermatic 350
Pin
1 +2.5 to 22 volts DC with respect to RC13-3, spool gun trigger closed, and min to max of spool gun wire
feed speed
2 Not used
3 +2.5 to 22 volts DC with respect to RC13-1, spool gun trigger closed, and min to max of spool gun wire
feed speed
1 17.7 volts AC with respect to RC14-3
2 Not used
3 17.7 volts AC with respect to RC14-1
1 Less than 1 ohm with respect to RC64-2
2 Less than 1 ohm with respect to RC64-1
Values
TM-1327 Page 59