Digital Equipment LGplus Series, Setup Manual

Page: 131 / 194

5–7
Centronics Interface Signals
The Centronics interface signals between the host computer and the printer
are defined as follows:
Data Lines 1 through 8 — Provide eight standard or inverted levels from
the host that specify character data, plot data, or a function code. Data Line 8
allows access to the extended ASCII character set. You may enable or disable
this line via the Data Bit 8 parameter on the Centronics submenu (see
Chapter 4).
Data Strobe — Carries a low true, 100 ns minimum pulse from the host that
clocks data into the printer.
Paper Instruction (PI) —Carries a VFU control signal from the host with
the same timing as the data lines.
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.
Online — A high true level from the printer to indicate the printer is ready
for data transfer and the ON LINE key on the operator panel has been
activated. When the printer is in Ready mode, it may accept data from the
host.
Paper Empty (PE) — A high true level from the printer to indicate the
printer is in a fault condition.
Busy — A high true level from the printer to indicate the printer cannot
receive data.