Epson EPL-6000 User Manual page 200

Transmission procedures
Ready/Busy:
The DTR signal level changes to HIGH when the printer is ready
l
to receive data (or to LOW if set for inverted operation by
SelecType).
The DTR signal level changes to LOW when the printer is not
l
ready to receive data (or to HIGH if set for inverted operation by
SelecType).
XON/XOFF:
When the printer is ready to receive data, it sends an XON
(11
hex) to the host computer through the TD line for the
RS-232C interface or SD+ and SD- lines for the RS-422A
interface. When ROBUST-XON is set to ON (by SelecType), and
data is not received within one second of the XON signal being
sent, the printer sends an XON signal every second. If ROBUST-
XON is set to OFF, the printer sends only one XON signal.
When the printer is not ready to receive data, it sends an XOFF
(13 hex) to the host computer through the TD line for the
RS-232C interface or SD+ and SD- lines for the RS-422A
interface.
The printer is ready to receive data when it is on line, no error
conditions exist, and the buffer is not filled above the overload
value set with SelecType.
The printer is not ready to receive data when it is off line or
when it is on line but the remaining capacity of the data buffer is
less than the overload buffer value.
Interface Specifications
Technical Specifications B-11