Prevention Hosts From Data Transfer Time-Out; Interface Selection - Epson Stylus Photo Service Manual

EPSON Stylus Photo

1.3.4 Prevention Hosts from Data Transfer Time-out

Generally, hosts abandon data transfer to peripherals when a peripheral is in the busy state for dozens of
seconds continuously. To prevent hosts from this kind of time-out, the printer receives data very slowly,
several bytes per minute, even if the printer is in busy state. This slow down is started when the rest of the
input buffer becomes several hundreds of bytes. Finally, the printer is in the busy state continuously when
the input buffer is full.

1.3.5 Interface Selection

The printer has 2 built-in interfaces; the parallel interface and serial interface. These interfaces are
selected automatically.

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 is that receives data first is
selected. When the host stops data transfer and the printer is in the stand-by state for the
seconds, the printer is returned to the idle state. As long as the host sends data or the printer
interface is busy state, the selected interface is let as it is.

Interface state and interface selection
When the parallel interface is not selected, the interface got into the busy state. When the serial
interface is not selected, the interface sets the DTR signal MARK. When the printer is initialized or
returned to the idle state, the parallel interface got into the ready state, the serial interface sets the
DTR signal SPACE. Caution that the interrupt signal such as the /INIT signal on the parallel
interface is not effective while that interface is not selected.
Rev.A
1-19