Datamax ST-3210 Operator's Manual page 20

"Print Side Media Sensor" using Fan-Fold Stock –
With the ticket TOF Marks facing 'up' (toward you), place the
stock in the bottom of the printer. (If using an external supply,
route the ticket stock into the printer through the Rear or Bottom
Slots.)
Ensure that the Printhead Latch is in the 'Locked' position.
Rear Slot
Bottom Slot
Thumbscrew
Printhead Latch
12
Media
Guides
Ticket Stock
Unlocked
Locked
S-Class