United Networks Pvt. Ltd. Offers 4 / 8 Serial Port Data Switches. United Networks Pvt. Ltd. Supplies RS 232 based data communications products. 4 / 8 Serial Port Data Switches are used when one computer is used to connect up to 8 devices. 4 / 8 Serial Port Data Switches enables uploading / downloading data to / from up to 8 CNC machines [or devices] use a single computer. The selection of device [say CNC machine] is through manual rotary selector switch and the selection is indicated by LED indicators on the front panel. It is available in two different models.