Nortel DMS-100 Series Maintenance Manual page 136

3-14 ESA maintenance overview
Terminal status table
The TST has an entry for each line appearance the ESA processor can
handle. Each entry has 2 bytes and each byte contains a data structure. The
two data structures are:
Every line can have several call processing line states. The call processing
line states determine what the system does with a specific message. The
ESA CC first screens the line states of the messages. The call process
controller (CPC) handles the lines in the idle, originate, abandon, or lockout
states. The CPC also handles the lines in the call-processing-busy state.
These lines are processed based on the call processing state in the CPBs of
each line. The CPC ignores the lines in the system busy (SysB) or manual
busy (ManB) states.
Refer to the following figure for a diagram of the TST.
Terminal status table
Line
640
The first byte (unprotected line data) in the TST is divided as follows:
297–8351–550 Standard 04.01 August 1999
Unprotected line data (ULD): The ULD helps the ESA CC decide what
action to take when an event message arrives from a terminal. An event
message establishes or changes a line state. The ULD also keeps track
of errors that a line generates during call processing.
ESA call process block (CPB): The ESA CPB stores the number of
re-origination attempts for a line. After the completion of an origination,
the TST stores the index of the call in a CPB.
Byte 1
5 4
7 6
0 Error count/cause
Error count/cause
Error count/cause: The first 4 bits contain the count of the errors that
line software detects. Each error increases the count. If the error count
reaches a preset threshold, the system takes the line out of service. The
last cause of the error is recorded in place of the error count.
Line state: The last 4 bits contain the current state of the line. The line
states are:
2 1
3 0 7
Line state
Line state
Byte 0
5 4 2
6 3
CPB index/origination count
CPB index/origination count
1
0