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 Multipoint Tributary Protocol
Envoy Application Programming Manual—427159-001
5-9
File-System Procedures
FILEINFO
Returns error information and characteristics about an open line.
OPEN
Establishes communications with a line. A line can be opened by only one process
(and its backup) at a time.
READ
Monitors the line for polling and selection sequences and accepts data from the
supervisor station. A call to READ while the line is in the CONTROL state (an
initial READ) causes Envoy to monitor the line.
If a polling sequence is received for one of the defined stations, and the station’s poll
state is inactive, Envoy responds to the poll with an EOT sequence (the READ does
not complete). If the station’s poll state is active, the READ completes with an error
166 (address has been polled) and with the line in the WRITE state. The address-list
entry number of the station that was polled is returned to the line buffer of the
application process.
If a selection sequence is received for one of the defined stations and the station’s
select state is inactive, Envoy responds to the selection with an RVI sequence (the
READ does not complete). If the select state is active, the first message is read from
the supervisor station and the READ completes with an error 0 (operation
successful) indication. The address-list entry number of the station that was selected
is returned to the application process’s line buffer.
A call to READ while the line is in the READ state (continuation READ) causes
Envoy to acknowledge the preceding message with the proper ACK0/ACK1
sequence and to accept the current message, if any. The receipt of an end-of-
transmission (EOT) sequence causes Envoy to resume monitoring the line on behalf
of the application process; the READ receiving the EOT sequence does not
complete until an active station is polled or selected or an error occurs. A call to
READ while the line is in the WRITE state (that is, while the local station is
transmitting) causes an EOT sequence to be transmitted to the remote station. The
READ then acts as an initial READ.
A call to CONTROL 20 after a READ monitors the line for control characters
without sending an acknowledgment for the preceding message (reserved by the
READ). File-system errors are used to indicate what was received from the host.
SETMODE
Alters the line characteristics (Table 5-4).