Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
2.3.3.7 Loopback Configurations
The CM4 provides three loopback options: Line, Payload, and Equipment.
LINE LOOPBACK
Line loopback is useful for testing the integrity of the transmission path and the T1 connections
to the multiplexer. It takes the decoded T1 receive signal coming from the line receiver/jitter
buffer, and loops it back to the T1 line driver input. Receive data also passes on to the
demultiplexer.
PAYLOAD LOOPBACK
Payload loopback is useful for verifying the operation of the CM4 up to the bus interface to the
channel modules. Data also passes on to the receive side of the channel modules.
EQUIPMENT LOOPBACK
Equipment loopback is useful for testing individual channel modules in the multiplexer. It
loops the transmit signals at the multiplexer output back to the demultiplexer input. During
Equipment Loopback, the T1 output of the CM4 is an ALL ONES signal.
2.3.3.8 Microprocessor Control
The CM4 uses an 8-bit microprocessor to control the front-panel operator interface, remote interface,
T1 communications and other system level functions. The microprocessor is supported by several
peripheral chips which include nonvolatile RAM, a T1 transceiver chip, EEPROM, and an ACTEL
custom programmable gate array.
2.3.3.9 User Interface
The CM4 provides the user with the following two types of user interfaces: Front Panel Interface and
RS-232 Interface. Each of these interfaces is described below.
Front Panel Interface - The CM4 has switches and a four-character alphanumeric display on its
edge to enable the user to enter settings and display status information. Details on the
operation of the Front Panel Interface appear in Section 4 of this manual.
RS-232 Interface - The IMUX 2000 M-DACS multiplexer can be set up and monitored from a
data terminal connected to its RS-232 port. This connection can be made locally at the
controlled multiplexer shelf, or remotely at any other node of the T1 network. The
remote connection utilizes a Facility Data Link (FDL) channel and is not available if the
T1 link passes through a CSU interface. Details on the operation of the RS-232
Interface appear in Section 3 of this manual.
M-DACS-T1 RFL Electronics Inc.
October 16, 2012 2-31 (973) 334-3100
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