Rack Mounting-   Built into a cabinet that has a standard width of 19" or 23". All types of electronics and computing devices come in rack-mounted packages, including servers, test instruments, telecommunications components, tape drives and audio and video equipment. The units are bolted to the side frames. If equipment is not rack mountable, it can be placed on shelves. The height of a rack-mounted device is specified in a unit (U) measure or rack unit (RU). 1U (or 1RU) is 1.75" from top to bottom. For more information on how Uptime Devices products are mounted go to our home page.

RARP- (Reverse ARP) RARP is a TCP/IP protocol used by a diskless workstation to obtain its IP address. Upon startup, the client station sends out a RARP request in an Ethernet frame to the RARP server, which returns the layer 3 address for a layer 2 address (performing the opposite function of an ARP). For more information go to our home page.

Reboot- Causing the computer to start executing instructions. PCs and Macs contain built-in instructions in a ROM or flash memory chip that are automatically executed on startup. These instructions search for the operating system, load it and pass control to it. Starting up a large computer may require more button pushing and keyboard input. For more information go to our home page.

Redundant Circuits- Redundant Circuits are a set of electronic components that perform a particular function in an electronic system. (Refers to peripherals, computer systems and network devices that take on the processing or transmission load when other units fail.) For more information go to our home page.

Relay- An electrical switch that allows a low power to control a higher one. A small current energizes the relay, which closes a gate, allowing a large current to flow through. For more information go to our home page.

Resellers- Uptime Devices has a variety of resellers throughout the world which can be viewed on our Where to Buy page.

RIP- (Routing Information Protocol) A simple routing protocol that is part of the TCP/IP protocol suite. It determines a route based on the smallest hop count between source and destination. RIP is a distance vector protocol that routinely broadcasts routing information to its neighboring routers and is known to waste bandwidth. It also has a limit of 15 hops. If a route is advertised as having 16 hops, it is flagged as unreachable. AppleTalk, DECnet, TCP/IP, NetWare and VINES all use incompatible versions of RIP. For more information go to our home page.

RJ-45- (Registered Jack-45) A telephone connector that holds up to eight wires. RJ-45 plugs and sockets are used in Ethernet and Token Ring Type 3 devices. RJ-45 Connectors Eight-wire RJ-45 connectors are used with Ethernet and Type 3 Token Ring networks. For more information go to our home page.

RS-232- (Recommended Standard-232) A TIA/EIA standard for serial transmission between computers and peripheral devices (modem, mouse, etc.). Using a 25-pin DB-25 or 9-pin DB-9 connector, its normal cable limitation of 50 feet can be extended to several hundred feet with high-quality cable. RS-232 defines the purpose and signal timing for each of the 25 lines; however, many applications use less than a dozen. RS-232 transmits positive voltage for a 0 bit, negative voltage for a 1. In 1984, this interface was officially renamed TIA/EIA-232-E standard (E is the current revision, 1991), although most people still call it RS-232. For more information go to home page.

RS-485- A TIA/EIA standard for multipoint communications lines. It can be implemented with as little as a wire block with four screws or with DB-9 or DB-37 connectors. By using lower-impedance drivers and receivers, RS-485 allows more nodes per line than RS-422. For more information go to our home page.