Black Box ME760A-R2, User Manual

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LDM-MR19.2
4. Card Installation
The ME760C is a card version of the LDM-MR19.2 that can be easily installed in
our RackNest 2/14. Its front-panel indicators and controls are arranged vertically
rather than horizontally, but (with the exception of its “extra” RPF LED and reset
button) they work exactly the same way as the indicators and controls with the
same names on the front panels of the standalone ME760A-R2 and ME760AE-R2
units; refer to Section 5.1. The controls on the card’s circuit board also function
the same way as those on the circuit boards of the standalone units, although the
card doesn’t have the RPF jumper; compare Table 3-3 and Figure 3-2 on pages 24,
25, and 27 with Table 4-2 and Figure 4-3 on pages 34 through 36. The main
difference between the card and standalone versions is that where the standalone
units have their own DTE and line connectors on their rear panels, the cards plug
into the RackNest 2/14 and use its connectors instead.
4.1 The RackNest 2/14
The RackNest 2/14 is a special 19" rack component designed to host a number of
our short-haul modems and line drivers. As shown in Figures 4-1 (on page 30) and
4-2 (on page 31), it consists of a rack chassis (with one or two power supplies) into
which you can plug as many as 14 modem or driver cards.
The Nest’s rear panel consists of fourteen five-screw terminal blocks (“TB1”)
for line interfaces and fourteen DB25 connectors (“J1”) for DTE interfaces.
Each terminal block (“TB1”) provides four screws for connecting the Nest-to-
Nest G.703 transmit and receive lines—the transmit line or pair can be connected
to (one of) the terminals marked XMT, and the receive line or pair can be
connected to (one of) the terminals marked RCV—plus a fifth screw for optional
ground connection.
Each DTE connector (“J1”) is a DB25 female. The pinning of this connector
depends on the type of card installed in the corresponding slot, because cards
designed for different native DTE interfaces will present and expect different
signals on different pins. For the ME760C LDM-MR19.2 card, the pinning is
standard TIA RS-232-D.