It won't work

Hi all can anyone help, I am trying to use the inbuilt software plc in a Stanley alpha controller ( version 4) I'm using rslogix500 and a serial cable between the two com ports(rs232) , I have also tried null modem cable (no joy)I have tried most of the rs232 drivers in rslinx (df1 and so on)but have failed miserably so far. Information in user manual is limited at best. Does anyone have any experience with this set up ? Any help would be greatly appreciated, many thanks. Stu