Casio TE-3000S Dealer's Manual page 16

System configuration
Steps to define COM port/peripheral devices
After connecting peripheral devices, programming of I/O parameter table, printer connection table are necessary.
16
START
No
Connect Modem or PC?
Yes
Connect it to COM1 port.
No
Connect a scanner?
Yes
Connect it to COM2 port.
No
Connect a scale?
Yes
Connect it to COM3 port.
No
Connect a slip printer?
Yes
Connect it to free COM2 or COM3 port.
No
Connect external printer(s)?
Yes
Connect it (them) to free COM port(s).
END