I had a gadget that had a parallel port on it, the manufacturer of said product sold a really expensive adapter that allowed it to be used with USB. They said it was the only one they found that worked with the equipment consistently. They were right, I must have tried four adapters, and then I still had to spend the $125 on theirs. Maybe what they mean is something like that?
Dunno your specific case, but the "custom" cable of those sort are still just a lesser know standard to others, but still a standard pinout. There are not too many people manufacture their own custom cables for the applications, usually they will map and do it at the devices. Not 100% sure.
I have this VW dongle that is older db9 serial days but wanted to use it with the newer laptops, I posted at their sponsored forum and asked, their engineer were being vague and offer no help other than to try a specific usb to serial that is $50 or more that may or may not work, or get a new dongle from them... It was later that found out through a different project that there were nothing special about their cable. just that it was a lesser known standard on RS232 chips, means their USB to serial chip have an extra RS232 chip to invert the signals.... I did confirm that and make that dongle worked flawlessly on usb by just buying a $10 usb to serial dongle with an RS232 chip. either case the story is that there are only few standards pin outs, the vendor wants you to buy their cables and probably won't help you find a cheaper source for it,,, consider it as trade secret of some sort.
