Epson Stylus Pro 7500, Service Manual

Page: 31 / 274

EPSON Stylus Pro 7500 Revision A
Product Description Interfaces 31
1.3.4 Supplementary Items
RECEIVING BUFFER OPERATION
When receiving data via the parallel interface or Type B interface while in a state where no
error has occurred (including the Pause state), if the available capacity of the buffer drops to
4 KB or less, the printer receives at 1 byte/sec. and prevents the host from issuing a time
out.
If the available capacity of the buffer becomes 8 KB or higher, 1 byte/sec. reception is
canceled and reception stops when the available capacity is 32 bytes or less. When the
available capacity becomes 1K-byte or higher, reception at 1 byte/sec. is resumed.
INTERFACE SELECTION
It is possible to switch between the manual fixed selection function or auto selection
function to select the parallel, USB or optional interface.
However, if the USB interface is connected, it becomes impossible to use the parallel
interface, For this reason, only one of these interfaces, either the parallel interface or the
USB interface, can be connected to the host computer and they cannot be used in
combination.
o
Manual Fixed Selection:
One interface, the Parallel/USB interface, or the optional interface, can be
selected.
o
Auto Selection Function:
After the power is turned on, the interface from which data are first received is
selected. After that, if a predetermined period of time (fixed at 10 seconds) passes
during which the reception of data is stopped, the printer enters the idle state (a
state where no interface is selected), then selects the interface from which it first
receives data next.
o
Concerning interface selection and interface state:
• When an interface other than the parallel/USB interface is selected, the parallel
interface enters the BUSY state. At this time, the LH signal goes “L.” The
meaning of LH = L is that the power is cut off. That is, it means that the 1284
interface cannot respond. Therefore, a host computer requesting reverse
transmission must first check LH. In addition, the USB interface is in a state where
it sends a NACK response and refuses to receive data.
• When an interface other than the optional interface is selected, the OFF-LINE bit
is set in the Main Status Register (MNSTS).
• After the printer has been initialized, or when in the idle state (with no interface
selected), with the parallel interface in the ready state, the USB interface in the
state where it does not send a NACK response, set the OFF-LINE bit of the Main
Status Register (MNSTS) for the optional interface.
• The interrupt signal, like the /INIT signal of the parallel interface, is disregarded
while that interface is not selected and while in the Nibble mode or ECP mode.
INITIALIZATION
This printer is initialized by the following three methods.
1. Hardware Initialization
This is the method of initialization that is carried out when the power is turned on.
<Initialization Operation>
• Printer mechanism initialization
• Input data buffer cleared.
• Print buffer cleared.
• Setting of default values.
2. Software Initialization
Initialization is performed by executing the Initialize command (ESC@).
<Initialization Operation>
• Print buffer cleared.
• Setting of default values.
3. Panel Initialization
This is the initialization operation when the Pause button is pressed for 2 seconds or
longer, or when the /INIT signal is input.
<Initialization Operation>
• Paper is ejected (in the case of roll paper, the printed portion is skipped and if the panel
setting’s paper select is set on Auto cut, the paper is cut, and if the cutter is OFF, the