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
4-30
WRITE Procedure
The file-system errors applicable to an initial READ from the CONTROL state also
apply to an initial READ from the WRITE state.
WRITE Procedure
The WRITE procedure is used to select and transmit messages to a tributary station.
While messages are being sent, the line is in the WRITE state. The line returns to the
CONTROL state when the supervisor station sends an EOT sequence (to indicate the
completion of the transmission).
Initial WRITE
An initial WRITE (Example 4-10) causes Envoy, on behalf of the application process, to
select the tributary station indicated by the address-list entry number in the message
control word, bits 8:15 (the entry number is placed in the message control word by the
application process). If the tributary station returns a positive acknowledgment to the
selection, the message in the buffer of the application process is transmitted. The call to
the WRITE procedure is complete when the remote station acknowledges the message.
The successful transmission of the initial message is indicated by a condition code of
CCE upon completion of the WRITE. Following the transmission of the initial message,
the line is in the WRITE state.
Table 4-12
lists the file-system errors that can occur on an initial WRITE.
Example 4-10. Initial WRITE
Supervisor (Local) Tributary (Remote)
line state = CONTROL
CALL WRITE(...)
| (sel) EOT SYN-sel addr-ENQ -->
| <-- ACK0
| message 1 -->
| <-- ACK1
(WRITE completes)
error = 0
line state = WRITE
Table 4-12. Initial WRITE File-System Errors (page 1 of 2)
Error State Description Resultant Line State
0 No error. The tributary station is selected and the
message in the buffer of the application process is
written to the tributary station.
WRITE
160 Request is invalid for device state; protocol error. unknown
161 Impossible event occurred for line state. unknown
163 EOT received. An EOT was received while wait-
ing for an acknowledgment of the first message
sent.
CONTROL