
Note :  The simplest way to connect to other hosts (not PC compatible) or 
terminals is: 
Pin 9 on OS-204/214/314 and pin 1 on OS-203 are reserved for 
KDU(keyboard device unit), therefore do not connect these 
pins if you are using a general host like a PC. 
Connection with host: 
Host 25S  Printer 9P   Host 9S  Printer 9P 
(PC or compatible)  (PC or compatible) 
DTR 20  …… 1 DSR    DTR 4  …… 1 DSR 
DSR 6  …… 6 DTR    DSR 6  …… 6 DTR 
TX 2  …… 2 RX    TX 3  …… 2 RX 
RX 3  …… 3 TX    RX 2  …… 3 TX 
CTS 5  ……  7 RTS    CTS 8  …… 7 RTS 
RTS 4  ……  8 CTR    RTS 7  …… 8 CTS 
GND 7  …… 5 GND    GND 5  …… 5 GND 
Alternatively you can just connect the 3 wires in the following way. 
Host 25S  Printer 9P   Host 9S  Printer 9P 
(PC or compatible)  (PC or compatible) 
TX 2  …… 2 RX    TX 3  …… 2 RX 
RX 3  …… 3 TX    RX 2  …… 3 TX 
GND 7  …… 5 GND    GND 5  …… 5 GND 
pin 4           pin 4      
pin 5        pin 6     
pin 6        pin 7        
pin 20        pin 8     
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    Printer Terminal/Host
Pin 2- RxData  ………  TxData 
Pin 3- TxData  ………  RxData 
Pin 5- Ground  ………  Ground 
In general, as long as the data quantity is not too large and you 
use Xon/Xoff as flow control, it will be problem free. 
Baud rate: 2400, 4800, 9600, 19200 and 38400. 
(programmable by command) 
Data format : always 8 data bits, 1 start bit and 1 stop bit. 
Parity : always non parity 
Handshaking : XON/XOFF as well as CTS/RTS (hardware flow 
control). 
If you run an application with the bundled printer driver under 
Windows and use the serial port, you should check the above 
parameters and set the flow control to "Xon/Xoff "or "hardware". 
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