Unit installation

Chapter 1 Introduction Installation and Operation Manual
1-10 Functional Description FCD-E1
Bus Functions
The FCD-E1 system performs its various functions by controlling the flow of data
among the various user and main link interfaces in accordance with the
application requirements.
The flow of data is performed through the FCD-E1 buses, as shown in Figure 1-3.
FCD-E1 comprises several buses:
• TDM bus, which carries the data to the main link. The TDM bus serves as a
highway through which all the information processed by the FCD-E1 flows. The
information is deposited and collected in discrete time intervals, called timeslots
(one timeslot supports a data rate of 64 kbps – see Appendix C). The TDM bus
consists of two lines:
 TSER line – carries the transmit data to the main link interface. The other
interfaces deposit data on this line, in the timeslots specified by the
management subsystem.
 RSER line – carries the data received by the main link interface. The other
interfaces read their data from the timeslots specified by the management
subsystem.
Each FCD-E1 port deposits payload information received through its external
interface on one TDM bus line, and simultaneously collects the information to be
sent through the external interface from the other line. Therefore, considerable
flexibility is available with respect to routing, because each port has access to all
the payload information, and can be instructed by the management subsystem to
read and write the desired information in the desired timeslots of the FCD-E1
TDM bus.
• Clock bus, which carries the various clock signals used by the FCD-E1 system.
The FCD-E1 can lock its system clock (see the Timing section on page 1-6) to
various clock signals applied to its user ports, in accordance with the
application requirements.
• Two management buses:
 Address bus – carries routing information from the management subsystem
to the other subsystems.
 Data Bus – carries the internal management data.
Main Link Interface
The characteristics of the main interface are described in Main Link on page 1-2.
The main functions of the main link interface are described below.
Framer
The transmit path of the framer generates the E1 frame structure transmitted by the
corresponding port, in accordance with the selected framing mode. The frame
structure is generated by combining the data retrieved from the prescribed timeslots of
the TSER line with the framing overhead. The TSER line may also carry inband
management data generated by the management subsystem when the main link
framing mode is G732S (G732N). Unused timeslots are filled with the idle code.