Envoy Application Programming Manual
Table Of Contents
- What’s New in This Manual
- About This Manual
- 1 Application Programming With Envoy
- 7 ADM-2 Multipoint Supervisor Protocol
- 8 TINET Multipoint Supervisor Protocol
- 9 Burroughs Point-To-Point Protocol
- 10 Asynchronous Line Supervisor Protocol
- A ASCII Character Set
- B ASCII to EBCDIC Code Conversion
- C File-System Procedures
- D Statistics Messages
- E S-Series Changes to Envoy
- NonStop™ Himalaya S-Series Server Architecture
- G-Series Migration Considerations
- CBSENSEON and CFSENSEON Modifiers
- LEOTRESYN and NOLEOTRESYN Modifiers
- Treatment of Characters After the Termination Character
- Number of SYN Characters
- DTR Drop
- Reporting of Parity Error
- Half-Duplex Support for Asynchronous Lines
- Controller Replacement
- SYSGEN and COUP
- Unit Numbers
- FDX Line Changes
- No Support for Auto-Call Unit
- Glossary
- Index
BISYNC Centralized Multipoint Supervisor Protocol
Envoy Application Programming Manual—427159-001
4-21
Nonresponding Station List
Nonresponding Station List
The nonresponding station list is internal to Envoy. It keeps track of stations that do not
respond to polling. If a polled station 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 station list. Stations in the nonresponding station list are referred to as
being partially disabled. Partially disabled stations are not polled when a poll sequence
is performed.
Stations are removed from the nonresponding list and returned to the polling state in
either of the following ways:
•
By defining a new poll list to Envoy using the DEFINELIST procedure.
•
By calling the CHANGELIST procedure and specifying that all stations be removed
from the nonresponding list.
Note that if a station's poll state is set to disable polling, it is not be polled, regardless of
the above procedure.
The following example shows how to remove stations from the nonresponding list:
CALL CHANGELIST (linefnum, -2, 0);
IF < THEN ...
In this example, a function of -2 clears the nonresponding list. A subsequent call to
READ with the line in the CONTROL state, polls all stations whose poll states are
enable polling.
Using the nonresponding station list lets the application process implement a slow poll.
By periodically clearing the nonresponding list, the application process can detect
stations that are coming online. The application process, however, should keep track of
stations that do not respond within a predetermined number of polling cycles. The poll
state of any permanently nonresponding stations should be set to disable polling.
Note. If the nonresponding list becomes full (no stations respond), subsequent calls to READ
result in error 176 (poll sequence ended with no responder). A new list must be defined or all
stations must be removed from the nonresponding list. A poll operation is not retried for nonre-
sponding stations.