1）Connect the serial cable with the serial port, as below:
Figure 1 RS232 Port
Then turn on the printer.
2）For Windows device：Open the tool ：http://u.pc.cd/0AsrtalKand adjust the baud rate as below, which should be set to 19200, as well as your device.
Figure 2 Baud Rate Setting
3）For Mac device: Please download Thermalprintertool from the APP store, and then adjust the baud rate to 19200.