Specifications

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 Figure 1-34. This clock mode is usually required for
connection to DTE equipment.
MX-2100
Channel Timing
Mode DCE
KHS.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
Figure 1-35. 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
KHS.1
XMIT Clock
RCV Clock
Tai l- 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
(Figure 1-36). The clock signals are received from the modems serving the data
channel.