Nortel DMS-100 Series Maintenance Manual page 90

2-6 Signaling for RLCM-EDC
DMS-X message format
Bit
7
Byte
0
1
2
3
4
Drawer number
5
6
The DMS-X message header is in the first six bytes:
The number of bytes in the actual message or data can change . The CRC
occupies two bytes. The CRC detects transmission errors. The end of
message occupies a byte.
297-8381-550 Standard 02.02 April 1999
6 5 4 3
SOM
Destination task ID
Source task ID
Line number
Message data byte
(variable length)
.
.
.
CRC
EOM
The first byte specifies the start of message (SOM).
The second byte specifies the destination task identification (ID) of the
message. This ID identifies the process in the LCM that receives the
outgoing message.
The third byte specifies the source task ID. This ID identifies the LCM
task that sent the incoming message.
The next three bytes specify the task ID number.
2 1 0
Node
number
EOM =
SOM =
LCM =
ID
Message
header
LCM
task ID
Actual
message
End of message
Start of message
Line concentrating
module
= Identification