Epson Stylus Color 740 Service Manual

EPSON Stylus COLOR 440, 640, and 740 Chapter 1 Product Description
22
The followin
g
tables show t
y
pical input and output si
g
nal levels for the
interface
(
IEEE-1284 level 1 device
)
. Si
g
nal levels are based on TTL
standards.
Table 1-15. Typical Output Signal Characteristics
Table 1-16. Typical Input Signal Characteristics
NOTE: The input and output signals are active-high; the logic level is
considered HIGH at 3.0 volts or more and LOW at 2.0 V or
less. The receiver shall provide an impedance equivalent to
7.5K ohm to ground.
1.3.2.1 Host Data Transfer Timeout Prevention
Generall
y
, hosts abandon data transfer to peripherals when a peripheral
is BUSY continuousl
y
for dozens of seconds. To prevent this kind of
time-out, the printer receives data ver
y
slowl
y
, several b
y
tes per minute,
even if it is bus
y
. This slowdown starts when the remainder of the input
buffer drops under several hundred b
y
tes. In addition, the printer is
BUSY continuousl
y
when the input buffer is full.
1.3.2.2 Interface Selection

Manual Selection:
One of two interfaces can be selected throu
g
h the default settin
g
mode.

Automatic Selection
(
St
y
lus COLOR 740 onl
y)
:
Automatic interface selection is enabled in the default settin
g
mode.
In automatic interface selection mode, the printer is initialized to the
idle state when it is powered on. The printer scans the interfaces to
determine which interface receives data first, then selects that
interface for further data transmission. When the host stops data
transfer and the printer is in stand-b
y
for several seconds, the
printer returns to the idle state. The process is repeated each time
the printer is powered on.
The followin
g
notes explain how the selection of one interface affects
the condition of other interfaces:

When an interface other than the parallel interface is selected,
the parallel interface
g
oes into the BUSY state. The LH si
g
nal is
set to LOW, blockin
g
the power suppl
y
and preventin
g
a
response from the 1284 Active si
g
nal. This makes it necessar
y
for the host, which re
q
uires reverse transfer of data, to check the
LH state.

When an interface other than the serial interface is selected, the
serial interface sets the DTR si
g
nal MARK.

When the printer is initialized or returned to the idle state, the
parallel interface
g
oes into the read
y
state. The serial interface
sets the DTR si
g
nal SPACE
(
LOW
)
and resets the off-line bit of
the Main Status Re
g
ister
(
MNSTS
)
to an optional interface.
Parameters Minimum Maximum
Voltage -0.5 V 5.5 V
Current 0.32 mA
when V
out
= 2.4 V
12 mA
when V
out
= 0.4 V
Capacitance — 50 pF
Parameters Minimum Maximum
Voltage 0.8 V 2.0 V
Current 0.32 mA
when V
in
= 2.0 V
12 mA
when V
in
= 0.8 V
Capacitance — 50 pF

Epson Stylus Color 740 Specifications

General

Brand	Epson
Model	Stylus Color 740
Category	Printer
Language	English