Sorry, I didnt get finished. Contact the manufacturer of the hardware your trying to run for the longer cables.
Some cables are proprietary. For ex., graphtec plotters require a graphtec cable.
they said that the plotters needed their propietary cables.
The only thing proprietary about them cables is.
They are serial cables with a null modem pin config. In other words one of the wires is crossed to act as a null modem.
Thats it. And they are all over the net for about $5 bux,,