•Condition for serial communication differs between the host and the printer.
Verify the condition of communication between the host and the printer. Adjust the condition for communication between the host and the printer and try printing.

•Erroneous wiring of signal line for communication
Verify whether the wiring of signal line for communication is correct. If the wiring is erroneous, correct it and try printing.

•Print data received by the printer is not correct.
Data received by the printer may be different from the desired one due to communication timing or external noise.
Some products have the function of hexadecimal dump printing (function to print the data received by the printer in hexadecimal code).
Check the data received by the printer by using a line monitor or hexadecimal dump printing feature.
For the presence of absence of hexadecimal dump printing feature or method of using hexadecimal dump feature, refer to the user’s manual of the product in use.
The output timing of ACK and the release timing of BUSY may be changed by the memory switch depending on the product.
Change the output timing of ACK and the release timing of BUSY and try printing.
If interface cable is longer than necessary, take countermeasures to prevent the effect of noise and try printing.
Use twisted pair line for the material of interface cable as an example of countermeasure.