Parallel port blocking

I have a legacy Java program which handles a special card printer by sending binary data to the LPT1 port (no printer driver is involved, the Java program creates the binary stream).

The program was working correctly with the client's old computer. The Java program sent all the bytes to the printer and after sending the last byte the program was not blocked. It took an other minute to finish the card printing, but the user was able to continue the work with the program.

After changing the client's computer (but not the printer, or the Java program), the program does not finish the task till the card is ready, it is blocked until the last second.

It seems to me that LPT1 has a different behavior now than was before. Is it possible to change this in Windows? I've checked BIOS for parallel port settings: The parallel port is set to EPP+ECP (but also tried the other two options: Bidirectional, Output only). Maybe some kind of parallel port buffer is too small? How can I increase it?

Solution 1:

Please check the firewall settings and Antivirus if have any?