Datamax Mark II M-4206 Operator's Manual page 161

V max
in
V
IH
V
IL
I
OH
I
OL
V
OH
V
OL
M-Class
GPIO Port Specifications
5.5 VDC maximum input into any pin
3.8 VDC minimum (high level input voltage)
1.65 VDC maximum (low level input voltage)
-8 mA typical, - 25 mA maximum (high level output current)
8 mA typical 25 mA maximum (low level output current)
I = -8 mA, minimum 3.8 VDC
OH
I = 8 mA, maximum .44 VDC
OL
151