Nortel Meridian SuperNode SL-100 Reference Manual page 93

6-6 Feature implementation
The following functions are performed by the controller card:
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This feature is required to provide the controller card with messaging
capabilities with the XPMs through a DS30A link, using DMSX protocol and
format. Messages over the DS30A link adhere to the DMSX protocol and have
the following characteristics:
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The DMSX format adheres to the following structure:
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Packet data encompasses destination and source task IDs, peripheral processor
number, destination terminal ID, and data bytes that contain the actual
messages.
Set messages are translated for the following types of line cards:
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In the event of a transmission error, the controller card's S71 chip retries the
transmission. If the second attempt fails, the S71 discards the buffer and pegs
an error counter.
555-4001-129 Standard 08.01 November 2000
manages DMSX format message sequencing on the controller card's
C-side
resets the IPE when a reset message is received
transfers set messages to the sets
routes maintenance messages and call processing messages to the
appropriate processes
translates messages from station sets into DMSX format
routes messages from station sets to the XPM using DMSX protocol
byte oriented
half-duplex
handshaking is performed between communicating transceivers
start of message - two bytes
packet data
Cyclic Redundancy Checking (CRC) - two bytes
end of message - two bytes
Digital Line Card (DLC)
Analog Line Card (ALC)
Analog Message Waiting Line Card (MLC 500/2500 sets)