Black Box ME260A, Owner'S Manual

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10
MODULAR MODEM ELIMINATOR
General-Purpose Interface Modules
The general-purpose interface modules are:
• RS-232 Module (part number ME261C), EIA RS-232 (ITU V.24)
• V.35 Module (part number ME262C), ITU V.35
• X.21 Module (part number ME263C), ITU X.21/V.11
• V.36 Module (part number ME265C), EIA RS-449/RS-422 (ITU V.36/V.11)
These modules provide the corresponding electrical and physical interface. The
timing (clock) signals are transparently handled (via level converters, as for the
other interface signals). To enhance Module universality and allow operation
in various applications without requiring a cross cable, each of these interface
modules has a switch that selects between DTE and DCE operation. Note that
this switch also affects the flow of timing signals.
ITU G.703 Interface Modules
These interface modules provide ITU G.703 interfaces:
• G.703 (2 BNC) (part number ME266C), 64-kbps co-directional interface
• G.703 (DB15) (part number ME267C), 2.048-Mbps interface
• G.703 (DB15) (part number ME268C), 1.544-Mbps interface
Each G.703 interface module includes the corresponding line driver and line
receiver, clock-recovery functions, and a jitter attenuator. The G.703 1.544-Mbps
interface module uses B8ZS line coding, and the G.703 2.048-Mbps interface module
uses HDB3 coding.
The timing of the receive path is always derived from the recovered line signal,
whereas the timing of the transmit path can be selected via user jumpers in
accordance with system clock distribution requirements: locked to the recovered
receive clock (“loopback” timing), locked to the external clock, or an internal
oscillator.
You can choose any pair of interface modules, which means you can use any
combination of interfaces, as long as the technical limitations of the interfaces
(as specified in the applicable standards) are observed.
NOTE
The EIA RS-232 (ITU V.24) interface cannot be used at rates higher than
64 kbps. Therefore, ITU G.703 T1 (ME268C) and E1 (ME267C) interface
modules can only be used with the ITU V.35 (ME262C), EIA RS-449/
RS-422 [ITU V.36/V.11] (ME265C), and ITU X.21/V.11 (ME263C) interface
modules.