Epson TM-C3400BK Technical Reference Manual page 100

Setting the mode
1
Turn the printer on.
2
Display the printer driver window.
(See How to Use the Printer Driver on page 153
3
Select [Maintenance And Utilities] tab and click [Post-Printing Verification
Settings].
4
The [Post-Printing Verification Settings] window is displayed. Select [Post-
Printing Verification Settings] and click [Next].
100
for how to display the driver window.)