scubaguyjohn

I want to purchase an ISY994. I presently own a 2413U which is a USB-connected PLM. I understand the isy994 requires a 2413S which is a serial-connected PLM. However, since the 2413U is nothing more than a 2413S with a serial to USB converter built in (all the protocols are the same from what i understand), wouldn't a $2 usb to rj45 or usb to serial converter allow my 2413U to operate with the isy994 and avoid another $80 expense for a 2413S? Am i missing something? thanks, John.