Epson Photo750 manual Prevention of data transfer time-out on Host, Interface selection

EPSON Stylus Photo 750 Revision A

1.3.5Prevention of data transfer time-out on the

host

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

1.3.6 Interface selection

The printer has 3 built-in interfaces; Parallel I/F, Mac serial I/F and USB I/F. 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 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.

1.3.7 IEEE 1284.4 protocol

The packet protocol described by IEEE1284. 4 is supported on the parallel I/F and USB I/F. Three function modes of IEEE1284.4 protocol, “On”, “Off” and “Auto” are available for each I/F, and one of them is selected according to the value in EEPROM address 0Ah and 0Ch.

On: Communication in IEEE1284.4 packet mode is started by receiving a magic string(1284.4 synchronous commands). Until a magic string is received, other commdands are discarded.

Off: Communication is carried out in the conventional mode. A magnetic string(1284.4 synchronous commands) is discarded.

Auto: Communication is carried out in the conventional mode until a magic string(1284.4 synchronous commands) is received. By receiving a magic string, communication in IEEE1284.4 packet mode is started.

NOTE: The packet protocol of IEEE1284.4 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 operate over IEEE1284.

Product Description Parallel Interface 20