Digital Equipment LGplus Series, Setup Manual

Page: 128 / 194

5–4
Dataproducts Parallel Interface Signals
Dataproducts-compatible interface signals between the host computer and the
printer are defined as follows:
Data Lines 1 through 8 — Provides eight standard or inverted levels from
the host that specify character data, plot data, or a control 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 Dataproducts submenu (see
Chapter 4).
Data Strobe — Carries a high true pulse from the host when data is ready.
The data strobe remains high until the Data Request line goes false. The
active edge of the strobe signal can be configured as leading (default) or
trailing.
Paper Instruction (PI) — Carries a DAVFU signal from the host with the
same timing and polarity as the data lines.
Ready — Carries a high true signal from the printer when AC power and DC
voltages are present, paper is loaded properly, and the printer is not in a
check condition.
Online — Carries a high true signal from the printer when the Ready Line is
true and the ON LINE key on the control panel has been pressed. When the
printer is in Online mode, it may accept data from the host.
Demand/Data Request — Carries a high true signal from the printer when
the printer is ready to accept character data from the host. This signal
changes to false shortly after the leading edge of the data strobe signal.
Cable Verify — Two pins on the interface connector are jumpered together
to allow the user to verify proper installation of the interface connector.