Envoy Application Programming Manual

TINET Multipoint Supervisor Protocol
Envoy Application Programming Manual—427159-001
8-17
Nonresponding Terminal List
In the example above, terminal 2 (%041) is not polled when polling is initiated.
Selective Polling (After Calling DEFINELIST)
Example 8-7 shows how to enable polling for a specific terminal by means of a call to
the CHANGELIST procedure. The terminal to be enabled for polling is terminal %041
in the above example.
In this example, terminal 2, %041, is polled on the next pass through the poll list.
Nonresponding Terminal List
The nonresponding terminal list is a list, internal to Envoy, that Envoy uses to keep track
of terminals that do not respond to polling. If a polled terminal does not respond with
either an EOT sequence or a message within the timeout period specified for the line, its
address is entered into the nonresponding terminal list. Terminals in the nonresponding
terminal list are referred to as being "partially disabled." Partially disabled terminals are
not polled when a poll sequence is performed. Terminals are removed from the
nonresponding list and, therefore, returned to the polling state, by either of the following
ways:
•
Defining a new poll list to Envoy with the DEFINELIST procedure
•
Calling the CHANGELIST procedure and specifying that all terminals are removed
from the nonresponding list.
Note that if a terminal’s poll state is set to disable polling, it is not polled, regardless of
the above procedures.
The following example shows how to remove terminals from the nonresponding list:
In this example, a function of -2 clears the nonresponding terminal list. A subsequent
call to READ with the line in the CONTROL state polls all terminals whose poll states
are enable polling.
The use of the nonresponding terminal list permits the application process to implement
a slow poll. By periodically clearing the nonresponding terminal list, the application
process can detect terminals that are coming online. The application process, however,
should keep track of terminals that do not respond within a predetermined number of
polling cycles. The poll state of any permanently nonresponding terminals should be set
to disable polling.
Example 8-7. Selective Polling (After Calling DEFINELIST)
CALL CHANGELIST (linefnum,1,0); ! enable polling for entry 1
Example 8-8. Remove Terminals from the Nonresponding List
CALL CHANGELIST (linefnum, -2, 0);
IF < THEN ...