Epson TM-L500A RFID Technical Reference Manual page 64

Functions of each connector pin
Receive buffer full:
 When the remaining space in the receive buffer drops to 128 bytes, the printer status
 The printer ignores the data received when the remaining space in the receive buffer is 0
DSUB9 DSUB25
Pin no. Pin no.
1 —
2 3
3 2
4 20
5 7
6 6
64
becomes "buffer full" and it remains "buffer full" until the space in the receive buffer
increases to 256 bytes.
byte.
Signal Signal
name direction
NC — Not connected
RXD Input Receive data
TXD Output Transmit data
DTR Output <When RTS/CTS flow control is selected>
Indicates whether or not the printer power is ON.
SPACE indicates that the printer power is ON, and MARK
indicates that the printer power is OFF.
<When DTR/DSR flow control is selected>
Indicates whether or not the printer is BUSY.
SPACE indicates that the printer is ready to receive data,
and MARK indicates that the printer is BUSY.
The printer goes BUSY when the printer is made offline by
pressing down the On/Off Line button or when the receive
buffer is full.
GND — Signal ground
DSR Input <When RTS/CTS flow control is selected>
Indicates whether or not the host computer power is ON.
SPACE indicates that the host computer is ON, and MARK
indicates that the host computer is OFF.
Changing the setting of DIP switch or memory switch allows
this signal to be used as a reset signal for the printer. This
reset signal is used for detecting the MARK status of the
host computer and for resetting the printer.
<When DTR/DSR flow control is selected>
Indicates whether or not the host computer is ready to
receive data.
SPACE indicates that the host computer is ready to receive
data, and MARK indicates that the host computer is not to
ready to receive data.
When DTR/DSR control is selected, check the status of this
signal before transmitting data.
Function