Answer: garbled characters appear when printing the test page. this depends on what port (data cable) the receipt printer uses.

  
    A、 parallel port:

1、please check whether the data cable of the receipt printer is plugged in properly (turn off the printer and plug and unplug both ends of the data cable several times);

2、take the printer to another good computer and connect it to see if it can be used normally. if it can indicate the computer's lpt there is a problem with the port (printing port);

3、if it cannot print normally, please check whether the parallel port data cable is faulty (replace it with another good data cable). if it can print normally, it means there is a problem with the data cable;  

4、if it cannot print normally, please check whether there is a problem with the printer's interface (replace the interface card and plug it back in, if the contact is poor, replace it with another interface card). if it can print normally, it means the printer has poor contact or other faults;

    B、 serial port:

1、there is no matching baud rate (the baud rate of the printer and the port baud rate of the computer must be the same). the baud rate of the printer can be passed DIP switch to modify, the computer's port baud rate can be modified in the driver port configuration;

2、 the serial port line may be faulty, please replace it with another good data line;

3、 if the serial port of the printer has poor contact or other faults, please turn off the printer first, then plug and unplug the data cable a few more times, or replace the interface card with a good one;

4、the computer's serial port is faulty, please switch to another computer to test;

    C、 network port:

1、if the network cable is aging, please replace it with a good quality crystal head;

2、the network port is faulty, please update the network card driver or repair the motherboard;

3、there is a large source of interference where the network cable passes, please stay away from the source of interference;

    D、USB mouth:

1、please update USB drive;

2、USB the interface contact is poor, replace it with another good one. USB for oral use (it is recommended to use the USB mouth).