Argox R-400plus User Manual page 61

Alternatively you can just connect the 3 wires in the following
way.
Host 25S
(PC or compatible)
...... 2 RX
TX 2
...... 3 TX
RX 3
GND 7 ...... 5 GND
pin 4
pin 5
pin 6
pin 20
The most simple way to connect to other hosts (not PC
compatible) or terminals is:
Printer
Pin 2- RxData .........
Pin 3- TxData .........
Pin 5- Ground .........
In general as long as the data quantity is not too large or you
use Xon/Xoff as flow control, there will be no problem at all.
Baud rate: 600, 1200, 2400, 4800, 9600, 19200 and 38400.
Printer 9P Host 9S
(PC or compatible)
...... 2 RX
TX 3
...... 3 TX
RX 2
...... 5 GND
GND 5
pin 4
pin 6
pin 7
pin 8
Terminal/Host
TxData
RxData
Ground
61
Printer 9P