MX-2100/2104
Installation and Operation Manual
Chapter 1 General Information
Application Considerations
1-45
Data Channel Clock Modes
MX-2100 provides several clock modes for data channels. The following various
system I/O modules support all, or some of these modes.
•
Clock Mode 1 - DCE.
In the DCE clock mode, the MX-2100 channel provides
transmit and receive clocks for the equipment connected to the data sub
channel, as shown in
. This clock mode is usually required for
connection to DTE equipment.
MX-2100
Channel Timing
Mode DCE
KH
S
.1
DTE
XMIT Clock
RCV Clock
Figure 1-34. Clock Mode 1 (DCE)
•
Clock Mode 2 - DTE1.
In the DTE1 clock mode, the MX-2100 data channel
sends data accompanied by clock to the connected equipment and accepts
data from the equipment according to the equipment clock, as shown in
. In this mode, an elastic buffer (FIFO) is used in the receive path of
the channel to absorb timing jitter. For KLS.1 data modules, the elastic buffer
size is
±
2 bits; for KHS.1 data modules, the buffer size is
±
4 bits.
This clock mode is usually required for "tail end" connections, when a DCE is
connected to a data sub channel, and its timing is locked to the MX-2100
timing.
DCE
Channel Timing
Mode DTE 1
KH
S
.1
XMIT Clock
RCV Clock
Tail-End
Circuit
MX-2100
Figure 1-35. Clock Mode 2 (DTE1)
•
Clock Mode 3 - DTE2.
In the DTE2 clock mode, the MX-2100 data channel
transmits and receives data according to the clock received from the modems
that connect it to the transmission equipment.
To compensate for jitter and short-term instabilities, elastic buffers are used at the
input and output of each channel (
±
2 bits for KLS.1 data modules, and
±
4 bits for
KHS.1 modules).
The DTE2 clock mode is required in various applications, such as data channels
connected to a digital data switch. The data switch provides the clock signal for
both MX-2100 and the equipment connected to MX-2100
(
). The clock signals are received from the modems serving the data
channel.
