Brother HL-1660E User Manual page 56

USER'S GUIDE
3–6
Notes
When you use the automatic interface selection, note the following:
Once the interface is automatically changed, it is not changed again
for a short period of time. This time period is called "Time Out" and it
can be set with the MODE switch. The factory setting is 5 seconds.
The communications parameters [ baud rate, code type, parity, stop
bit, Xon/Xoff, DTR(ER), and Robust Xon] must be set for the serial
interface. Although they have been factory set as shown in the above
table, you may need to change them with the MODE switch.
This function takes a few seconds to work. If you want to speed up
printing, select the required interface manually with the MODE
switch.
If you constantly use only one interface, we recommend that you select
that interface in the interface mode. The printer allocates all of the input
buffer to that interface if only one interface is selected.