You have too k ow if you have a usb to serial converter cable.
1. Do not plug it into the pmc8
2. Plug it into a pc
3. Open the device manager. See if it is listed there as a comm port or usb to serial. If not it is not a converter or you have not loaded a driver for it. Check for that
I bought a great cable for 15$ so it is not impossible that your 12$ cable is an ftdi cable. But you should be able to tell as it will need to have a back shell over the DB9 connector inside of which is the chipset. Many have an led that lights when the thing is plugged into the computer.
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired