Printronix L5520 - Manual (Page 226)

Appendix C Host I/O Interfaces
226
Centronics Parallel Interface Signals
The Centronics interface signals are defined below:
• PAPER EMPTY (PE) - A high true level from the printer to
indicate the printer is in a fault condition.
• SELECT - A high true level from the printer to indicate the
printer is ready for data transfer and the ONLINE key has been
activated.
• BUSY - A high true level from the printer to indicate the printer
cannot receive data.
• ACKNOWLEDGE - A low true pulse from the printer indicating
the character or function code has been received and the
printer is ready for the next data transfer.
• DATA STROBE - A low true, 100 ns minimum pulse from the
host to clock data into the printer.
• DATA LINES - Eight standard or inverted levels from the host
that define the data, which may consist of a character or
function code. Sensing Data Line 8 is controlled by printer
configuration.
• PAPER INST - Optional VFU control signal from the host with
the same timing and polarity as the data lines. Sensing of the
PAPER INST line (PI line) is controlled by printer configuration.
• PRIME - Optional low true signal from the host used to reset
the printer to its default power-up state.
• NFAULT - A low true level from the printer to indicate the
printer is in a fault condition.
NOTE: The PAPER INST line must be disabled (configuration
option selected from the control panel) if the host computer
does not drive or control it. If the line is not controlled by the
host and PAPER INST line sensing is enabled in the
printer, rapid paper slewing occurs.