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1.3.2 Serial Interface
This printer can use the optional LocalTalk/serial interface module.
Type: RS-232C/current loop
Transfer system: Full duplex
Synchronization: Asynchronous start-stop system
Start-bit: 1 bit
Stop-bit: 1 or 2 bits
Data length: 7 bits or 8 bits
Parity: Odd, even, or none
Protocol: X-ON/X-OFF (can be combined with DTR control)
DTR control (can be combined with X-ON/X-OFF)
Transfer speed: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, or 57600 bps
Error: Overrun error: Processed as missing data and replaced by “*”
Parity error: Replaced by “*”
Framing error: Replaced by “*”
Breaking character: Ignored
Signal description: See Table 1-10.
Table 1-10. Serial Interface Pin Assignments
Pin No. Signal Name I/O Description
1
CHASSIS-GND
—
Connected to the printer chassis. The printer chassis GND and
signal GND are connected to each other.
2
TXD
OUT
Serial ASCII data output by the printer. It maintains the
“MARK” state (LOW level) between transmitted character
codes. Logic 0 is at HIGH level (SPACE) and logic 1 is at LOW
level (MARK).
3
RXD
IN
Serial ASCII data input to the printer. It maintains “MARK”
state (LOW level) between received character codes.
5
CTS
IN
Always ignored.
7
SIGNAL-GND
—
Ground.
17
TTY-TXD
OUT
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 being sent indicates that the printer is
busy.
20
DTR
OUT
Signal output by printer. When the DTR signal is HIGH, the
printer can receive the RXD signal. The SelecType settings do
not specify DTR control, the signal level is HIGH while printer
power is on. When the SelecType setting is used for DTR
control, DTR goes LOW in case of any error conditions. The
data (RXD) from host computer must be stopped within 128
characters after DTR goes LOW.
23
TTY-RXD Return
—
Current loop signal: Current return for pin 17
24
TTY-TXD Return
—
Current loop signal: Input data current loop
25
TTY-RXD
IN
Current loop signal: Current return for pin 25
Note :
The DTR state can be selected through printer settings.
EPL-5500 Service Manual General Description
Rev. B 1-15