Epson Stylus Color 760, Service Manual

Page: 18 / 172

EPSON Stylus COLOR 760 Revision C
PRODUCT DESCRIPTION INTERFACE 18
1.3.4 Preventing Data Transfer Time-out of Hosts
Generally, hosts abandon data transfer to peripherals when a peripheral is in
the busy state for dozens of seconds continuously. To prevent this kind of time-
out, the printer receives data very slowly, several bytes per minute, even if the
printer is in the busy state. The slowdown starts when the remaining input
buffer becomes several hundreds of bytes. Finally, the printer gets into the
busy state continuously when the input buffer is full.
USB and IEEE1284.4 on the parallel interface do not require this function.
1.3.5 Interface Selection
The printer has two built-in interfaces: the USB and parallel interface.
These interfaces are selected automatically.
o
Automatic Selection
In this automatic interface selection mode, the printer is initialized to the
idle state scanning which interface receives data when it is powered on.
Then the interface that received data first is selected. When the host stops
data transfer and the printer is in the stand-by state for seconds, the printer
is returned to the idle state. As long as the host sends data or the printer
interface is in the busy state, the selected interface is let as it is.
o
Interface State and Interface Selection
When the parallel interface is not selected, the interface gets into the busy
state. When the printer is initialized or returned to the idle state, the parallel
interface gets into the ready state. Note that the interrupt signal such as the
-INIT signal on the parallel interface is not effective while that interface is
not selected.
1.3.6 IEEE1284.4 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.
o
Automatic Selection
An initial state is compatible interface and starts IEEE1284.4
communication when magic strings (1284.4 synchronous commands) are
received.
o
On
An initial state is IEEE1284.4 communication and data that received it by
the time it is able to take synchronization by magic string (1284.4
synchronous commands) is discarded.
o
Off
An initial state is compatible interface and never starts IEEE1284.4
communication even if magic strings (1284.4 synchronous commands) are
received.