I spent days trying to get my used CP-2500 working and I wanted to share what worked for me. I began by trying to use the USB cable and the computer never seemed to recognize it because there was never a "New Hardware Found" alert. I moved on to the serial cable, which I never got working. I used a RS-232 serial adapter with a straight-thru cable first with no response. I tried the RS-232 adapter with a 9-pin to 25-pin cable and it saw the cutter because SignBlazer was sending data, but it would never start cutting. I tried a null cable, which I made, with the RS-232 adapter with no results. I also tried it without pins 6 and 1 being shorted with no results. I ordered the Tripp-Lite Keyspan RS-232 adapter because some said that was the only one that would work. I continued to try different things and once I had given up and had no choice but to wait on the new adapter, I plugged the USB back in. No "New Hardware" popped up, but I did still have Device Manager open and I noticed that a serial port had been added. I went into the properties and advanced settings on the serial port and changed it to COM1 and it worked! Just thought I would share since I would have pulled my hair out this weekend - if I had any!