This option, when added to a System 3505/3500/3000, enables connection to the Multiplex equipment offered by Digitize. The line driver rack is used to provide a mix and match capability for a variety of data protocols, such as polling radio, RS-422/485, audio, fiber optics, RS-232, and high level drivers. The line drivers also provide line-to-line isolation so that all DGM's are not on the same line. This is especially important when the multiplexing system is used for campus-wide monitoring. Power for the card rack is supplied by the System 3505/3500/3000. Each card rack holds 32 line drivers and can be expanded to up to four card racks, totaling 128 isolated lines.