Hi, I am having trouble interfacing an HP86B to an HP7040 plotter with a serial interface. I have two HP serial interfaces: standard with male DB25 connector and 0pt.01 with female connector. The plotter has a male DB25 connector. I have connected the standard with with a gender changer and the opt. 01 directly without success. I typed PLOTTER IS 10 and (the baud rate on the plotter is set at 9600)I get an error message. This is the first time I have tried a serial connection and unfortunately I don't have any documentation for the HP serial interface. Do I need a null modem for the opt. 01 serial interface? What am I doing wrong? Thanks, Bob