Service manual

TTY-TXD
Current loop signal:
HIGH impedance (SPACE) between pins 17 and 24 or X-ON signal
sent across pins 17 and 24 indicates that the printer is ready to
accept data; LOW impedance (MARK) or X-OFF signal sent
indicates that the printer is busy.
TTY-RXD Return
Current loop signal: Current return for pin 17.
TTY-TXD Return
Current loop signal: Input data current loop.
TTY-RXD
Current loop signal: Current return to pin 25.
Protocol
There are two types of protocols, as listed below, and each of them can be designated by the
SelecType independently.
❒ DTR/DSR protocol
The DTR/DSR control protocol can be selected by SelecType. The DTR signal is set to a HIGH level
when the printer is ready to receive data, and to LOW when an error is detected. DTR remains
HIGH when SelecType is set to OFF for DTR control. The printer sends only TXD off when the DSR
signal is HIGH. (DSR signal is always assumed HIGH when select mode for DSR is set to OFF.
X-ON/X-OFF transmission is independent of DSR.
❒ X-ON/X-OFF (DC1/DC3) protocol
Select mode is used to execute X-ON/X-OFF protocol. The X-OFF (DC3) code, transmitted by error
detection, warns the host computer to stop sending data within 128 characters. No further X-OFF
codes are sent in response to additional data sent from the host computer after the warning has
been given once. An X-ON code is transmitted when all the errors are cleared. The X-OFF code is
transmitted only once when the remaining capacity of receiving buffer drops under for 128
characters, or any error occurs. The X-ON code is sent when the printer is powered on. The
SelecType setting can be used to withhold X-ON/X-OFF code transmission.
EPL-N2000 Service Manual Product Description
Rev. A 1-25