You mentioned the instrument and the computer between the digital-to-analog converter, I guess there may be 232-422/485 communication module of the thing, or a special communication module, the computer side of the general for the serial port or USB, if you are using the computer with the 232 port, from the computer design itself, he is not with surge protection, but the computer side of the computer to do if you want to do the data transceiver, USB and the same. It is the same.