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
4-7
Limited Conversational Mode
procedure. Therefore, the application process at the supervisor station must process the
message within the timeout period specified for the tributary station.
If message-processing time is longer than the timeout period of the tributary station, the
application process at the supervisor station should send a wait-for-acknowledgment
(WACK) sequence at periodic intervals (this can be accomplished by calling the
CONTROL 14 procedure).
Limited Conversational Mode
The use of limited conversational mode lets the supervisor station, following selection of
a tributary station, make a conversational reply in place of a positive acknowledgment.
The application process calls the WRITEREAD procedure to make the reply and to
accept a subsequent message from the tributary station.
File-System Procedures
The application process uses the following Guardian 90 file-system procedures to
interact with Envoy and to communicate with the tributary stations:
AWAITIO
Waits for completion of an outstanding nowait I/O operation.
CHANGELIST
Performs any of the following functions:
•
Enables or disables polling or selection of a particular station
•
Alters the polling type (from continuous to noncontinuous or vice versa)
•
Causes Envoy to resume polling of partially disabled (nonresponding) stations
CHANGELIST may be called while polling is in progress, but will not take effect
until polling stops.
CLOSE
Terminates access to a data communications line.
CONTROL
Performs the various line control operations (Table 4-4).