Kostas, SV1DPI wrote: "I need help for the null cable to connect my markv with a computer com (9 pin). I made many tests with no success. Which is exactly the pins ?" ========== A null modem cable will not work because two pins are reversed. You need a cable that is wired pin 1 to pin 1, pin 2 to pin 2, etc. 73, de Earl, K6SE