Dplc Channel Multiplexer - ABB ETL600 Instruction Manual

ABB Switzerland Ltd
3.5.3.1.

DPLC Channel Multiplexer

The multiplexer combines up to 9 individual channels into a single
aggregate channel. The data transfer rate, interface and data transfer
format (synchronous, asynchronous, anisochronous) can be set
individually for each of the individual channels. The aggregate channel
is transmitted trough the MOD600 modem.
The multiplexer transmitter adds a frame to the aggregate stream of
the MOD600 modem. Each frame has a duration of 10ms. This frame
duration is constant for every MOD600 data transfer rate.
As depicted in Fig. 3-37, the frame comprises a preamble word (PRE)
for synchronization followed by the individual channels (CHx). When
the aggregate data transfer rate is higher than the sum of all individual
channel rates plus the preamble, the frame is filled-up (FIL).
Each individual channel in this frame comprises a user data field
(UDF) of the length of nominal bit rate increased by two bits (ADJ).
This allows speed adjustment for tolerances of connected DTEs
Frame [10 ms duration]
PRE
UDF
PRE Preamble field (length: 9 bit)
CHx Channel x (individual transmission channel)
UDF User Data Field (length: nominal bps)
ADJ Speed adjustment (length: 2 bit)
FIL Frame fill-up (length: variable)
Fig. 3-37
Note:
The required gross data rate for each MOD600 profile can be
calculated according to the following formula:
[ ]
GrossDatar ate bit/s
where:
GrossDatarate is the required aggregate rate of MOD600 modem;
NetDatarate is the sum of all individual channel data transfer rates;
3-50
1KHW001489-EN
CH1 CH2 .......
DPLC Channel Multiplexer Framing
When defining the data transfer rate of the aggregate
channel for configuration, note that the framing
overhead depends on the number of individual
channels transmitted.
[ ]
= +
NetDatarat e bit/s
November 2005
CHn FIL
ADJ
[ ] [ ]
(
1000
× +
[ ] 9 bit 2 bit
10 ms
Structure and Function
ETL600
)
×
Channels