Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
11.2 OVERVIEW
The IMUX 2000 Optical Interface Adapters (OIAs) provide a redundant (or non-redundant) T1 or E1
optical interface between IMUX 2000 Multiplexers in a network. External timing (input and output),
and RS-232 communication are also provided. These OIAs can only be used with CM4 Modules that
support CMI encoding.
The OIA consists of two sub-assemblies which are mounted together to form one OIA module. One of
the sub-assemblies is the MA217A Redundant I/O Board, and the other sub-assembly is the Light
Interface Board (LIB) of which there are five types. Each sub-assembly has a 30-pin female connector
that mates into an adjacent physical slot at the rear of an IMUX 2000 chassis, and interfaces with one
of two CM4 Modules (Main or Standby) through the motherboard.
The MA-217A contains the control logic and relays required to switch transmit and receive signals,
RS-232 signals, and external timing signals between the Main and Standby CM4 Modules. The RS-
232 and external timing ports are physically located on the MA-217A module.
The LIB sub-assembly contains both the emitter and the photodiode detector circuitry. The transmit
section consists of the LED or Laser emitters, and the current driver circuit. The receive section
consists of the fiber optic photodetector, a switched-gain trans-impedance amplifier, several stages of
amplification, and a Schmitt trigger limiter.
11.3 MA-217A SUB-ASSEMBLY AND REDUNDANCY OPERATION
For the following discussion, refer to the block diagram shown in Figure 11-2. The signals that pass
through the MA-217A to and from each CM4 module (Main CM4 and Standby CM4) include T1 or
E1 input/output, external timing input/output, RS-232, and other control signals. In general, either the
Main or Standby signals are active. The Main signals are active when relays K1 through K4 are de-
energized. The Standby signals are active when K1 through K4 are energized by an active low relay
enable signal. A signal from the Standby CM4 determines if the Main or Standby CM4 is to be
“active”.
In normal operation, the Main CM4 is active and the Standby CM4 is monitoring the Main CM4 back
plane signals. Signals pass to and from the Main CM4 through the de-energized relays. A “switch”
from the Main to the Standby CM4 occurs if the Standby determines that the Main card has failed.
This causes relays K1-K4 to switch, allowing signals to pass to and from the Standby CM4 through the
energized relays.
A miniature 6-position shielded and filtered modular jack provides an External Timing interface at the
rear panel. The external input timing can either be a 2.048mHz E1 or EIA-422 signal. Jumpers on the
CM4 module determine the type of input required. External output timing is always present at the
connector as an EIA-422 signal. Note that only an “active” CM4 can receive input or provide output
timing. The external input and output signals are surge and (ESD) Electro Static Discharge protected.
A male DB9 connector provides an RS-232 interface at the rear panel. The RS232 IN signal makes a
direct connection to both Main and Standby CM4 modules at all times. The RS232 OUT signal is only
possible with the active CM4 module. Provision is made for ESD and over voltage protection for input
and output RS-232 signals.
IMUX 2000E1 RFL Electronics Inc.
August 18, 2004 11-4 (973) 334-3100
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