Ieee 1284.4 Protocol - Epson SEIJ98006 Service Manual

EPSON Stylus Color 900


Interface state and interface selection

When an interface other than parallel interface is selected, the
parallel interface goes into the BUSY state.

When an interface other than serial interface is selected, the
serial interface sets the DTR signal to MARK.

When an interface other than optional interface is selected, the
printer sets "OFF LINE" bit of MNSTS register to the optional
interface.

When the printer is initialized or returned to the idle state, the
parallel interface enters ready state and the serial interface sets
the DTR signal SPACE and the printer resets "OFF LINE" bit of
MNSTS register to the optional.
NOTE:An interrupt signal, such as /INIT, on the parallel interface is
not effective while that interface is not selected.
Product Description

1.3.7.1 IEEE 1284.4 Protocol

The packet protocol described by IEEE1284.4 standard allows a device
to carry on multiple exchanges or conversations which contain data
and/or control information with another device at the same time across
a single point-to-point link. The protocol is not, however, a device
control language. It does provide basic transport-level flow control and
multiplexing services. The multiplexed logical channels are independent
of each other and blocking of one has no effect on the others. The
protocol operates over IEEE1284.


Automatic selection:
An initial state is compatible interface and starts IEEE1284.4
communication when magic strings (1284.4 synchronous
commands) are received.


ON:
IEEE1284.4 is enabled as initial state. Data sent before the magic
string (1284.4 synchronous commands) is discarded.


OFF:
IEEE1484.4 is disabled and IEEE1484.4 synchronous commands
are ignored. Compatible interface is the initial state.
Interface
Revision C
30