Telex 38109-977 manual KP-32 is a good example of an advanced user station keypanel

GPI (or GPI/O)

Rack Unit(s) (RU)

Figure 4.1 The KP-32 is a good example of an advanced user station (keypanel).

General Purpose Interface or General Purpose Input/Output. This refers to logical inputs and outputs that can be wired to external devices for various purposes (hence the term “General Purpose”). Typically, these are optically isolated logical inputs and relay outputs. However, other variations exist.

A standard unit of measure used when dealing with electronic equipment racks.

1 RU = 1.75” (44.45 mm). For example: a particular piece of equipment is described as being 3 RU in height. This means that it is 5.25” (3 x 1.75”) in height. Detailed information on the specification of standard electronic equipment racks can be found in EIA RS-310**.

**International Standard from Electronics Industry Alliance. See http:\\www.eia.org.

46 H a n d b o o k o f I n t e r c o m S y s t e m s E n g i n e e r i n g