Specifications

Chapter 1 Introduction Installation and Operation Manual
1-10 Functional Description FCD-E1LC Ver. 1.0
Synchronous Data Channels
Data Channel Interface Characteristics
The FCD-E1LC data channel is available with one of the following types of
interfaces: RS-530, V.35, X.21, or V.36/RS-449. All versions are supplied with a
25-pin D-type female connector.
V.24 interface equipment connects to the RS-232 port of the FCD-E1LC using a
standard straight cable.
All other interface versions are terminated in a 25-pin D-type female connector.
The conversion between the 25-pin channel interface connector and the standard
V.36, V.35, or X.21 interface connectors is made by means of adapter cables:
• V.36 interface: the adapter cable is terminated in a 37-pin D-type female
connector.
• V.35 interface: the adapter cable is terminated in a 34-pin female connector.
• X.21 interface: the adapter cable is terminated in a 15-pin D-type female
connector.
Suitable adapter cables can be ordered from RAD.
The data channel interface supports the following control lines:
• RTS – input from the local user’s equipment.
• CTS – output to the local user’s equipment. This line can be configured to be
always in the active state, or track the state of the RTS line.
• DSR – the DSR line is always active when the FCD-E1LC is powered, except
when a remote loopback is activated on the main link.
• DCD – the DCD line is active when the FCD-E1LC main link interface is
synchronized.
Data Channel Processing
The data channel operates as a synchronous port, which connects to the TDM
bus via a bus interface. The data channel performs two main functions:
• In the output (receive) direction, the bus interface reads the payload data
from the appropriate timeslots of the TSER line, under the control of the
management subsystem, and generates a continuous n × 64 kbps or
n × 56 kbps data stream. The data stream is accompanied by a clock signal
derived from the internal FCD-E1LC system clock.
The transmit data and clock signals are then applied to the channel interface,
which provides the interface to the external (user’s) equipment.
• In the input (transmit) direction, the user’s data applied to the input of the
channel interface is placed in the appropriate timeslots of the RSER line,
under the control of the management subsystem.
To enable synchronous operation, FIFO buffers are used to absorb timing
variations (jitter, wander, etc.). In all the data channel timing modes, the FIFO