Parallel port data bit pin 9 is used to control another added 120VAC SSR and is set to 3.3V or 5V when M7 code is active. SSR operates solenoid valve via 120VAC socket shown in next shot. Five pin DIN connector is now used since both pin 8 (spindle reverse) and pin 9 need to be monitored. DIN socket is also shown in next shot.