EPSON Stylus Scan 2500 Revision A

Product Description Interfaces 21

IEEE1284.4 PROTOCOL

The packet protocol described by IEEE1284.4 standard allows a device to
carry on multiple exchanges or conversations which contain data a nd/or
control information with another device at the same time across a single
point-to-point link. The protocol is not, however, a device con trol 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.
Automatic Selection
An initial state is compatible interface and starts IEEE1284.4
communication when magic strings (1284.4 synchronous comman ds)
are received.
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 disc arded .
Off
An initial state is compatible interface and never starts IEEE1284.4
communication even if magic strings (1284.4 synchronous
commands) are received.
1.5.2 Scanner interfaces

PARALLEL

1. Specification
Transmission mode 8 bit parallel, IEEE-1284 compatibility/nibble mode
Synchronization Refer to the IEEE-1284 specification
Handshaking Refer to the IEEE-1284 specification
Packet Refer to the IEEE-1284 Standard for Data Delivery
and Logical Channels for IEEE Std. 1284.4 Interface
(Draft D1.50)
Refer to the IEEE-1284 specification
Signal level TTL compatible level (IEEE-1284 Level 1 device)
Data trans. timing Refer to the IEEE-1284 specification
2. Connector pin assignment and signals
Refer to the IEEE-1284 specification
3. Data transmission timing
Refer to the IEEE-1284 specification