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APPENDIX
Appendix D: Serial Interface

D-1. RS-232C Connector

Pin No.
Signal name
Direction Function
25 Pin
9 Pin
1 F-GND —Frame ground
2 3 TXD OUT Transmission data
3 2 RXD IN Receive data
4 7 RTS OUT Same as DTR signal.
5 N/C Not used
8 CTS IN Status of this signal is not checked.
6 6 DSR IN STAR Mode
Status of this signal is not checked.
ESC/POS Mode
In DTR/DSR communication mode, indicates whether data receive
from host is enabled or disabled.
Space: Receive enabled
Mark: Receive disabled
(except when transmitting data by DLE EOT, and GS a)
This signal is not checked in the X-ON/X-OFF communication
mode.
7 5 S-GND —Signal ground
8~19 1,9 N/C Not used
20 4 DTR OUT STAR Mode
Indicates whether data receive from host is enabled or disabled.
1) DTR/DSR Communication Mode
Space when receive is enabled.
2) X-On/X-Off Communication Mode
Always space, except during following conditions:
• Period between reset and communication enabled
• During self printing
ESC/POS Mode
Indicates whether data receive from host is enabled or disabled.
1) DTR/DSR Communication Mode
This signal indicates whether the printer is busy. SPACE
indicates that the printer is ready to receive data, and MARK
indicates that the printer is busy. The busy condition can be
changed by using DIP SW 1-6 as follows: