EPSON FX-890/2190 Revision B
PRODUCT DESCRIPTIONS Interface 29
1.2.7 IEEE1284.4 protocol
The packet protocol described by IEEE1284.4 is supported on the parallel I/F.
Two function modes of IEEE1284.4 protocol, “Off” and “Auto”, are available and
one of them is selected according to the value of Default setting. (See Section
1.3.5. Default Setting).
NOTE:Packet protocol option “Off” &“Auto” in Default setting mode are effective in
not only parallel I/F but also USB I/F.
Auto: Communication is carried out in the convetional mode until a magic
string (1284.4 synchronous commands) is received. By receiving a
magic string, communication in IEEE1284.4 packet mode is started.
Off: Communication is carried out in the convetional mode.
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 operates over IEEE1284.