Printronix L5520 - Manual (Page 70)

Chapter 3 Host Interface Menus
70
If you enable the Series 1 Idle parameter, then whenever the buffer
is less than 75% full, the printer sends a response character to the
host every two seconds.
You can select the poll character and the poll delay time from the
printer control panel. You can also enable or disable Series 1 Idle
from the control panel. Descriptions of these parameters start on
page 69.
NOTE: When using the SERIES 1, 1 CH protocol, be careful with
the transmission of binary data (control codes, bit images,
etc.) since the printer discards poll characters.
SERIES 1, 2 CH
When you select the Series 1 with 2 Characters protocol, the printer
behaves exactly the same as the Series 1 with 1 Character
protocol, except that the printer sends two-character responses to
the host. These response characters are listed in the following
table:
NOTE: When using the SERIES 1, 2 CH protocol, be careful with
the transmission of binary data (control codes, bit images,
etc.) since the printer discards poll characters.
Online State Buffer State Response Characters
Online Buffer Empty 1 CR
Buffer Full 3 CR
Offline Buffer Empty 0 CR
Buffer Full 2 CR