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
5-12
Station address
Station address
Each entry in the address list is a station address. A station address has the following
form:
address-ENQ
Each station address (including the ENQ character) must contain exactly the address
size times two byte elements. All station addresses in a given address list are the same
size. Addresses containing an odd number of bytes must be padded with a leading SYN
character (%026) or a trailing NUL character (%0). (See Example 5-2
.)
Poll List
The poll list contains one entry for each station address that may be polled (the poll
count). The most significant bit of the first element of each entry in the poll list (that is,
station address.0) is the poll-state bit. The state of this bit indicates whether or not the
associated station has data to send:
0 = active, station has data to send. If a READ is outstanding and the station is
polled, the READ completes with an error 166 (address has been polled), the
line is placed in a WRITE state, and the address-list entry number of the polled
station is put in the message control word.
1 = inactive, station does not have data to send. If a READ is outstanding and the
station is polled, Envoy responds with an EOT sequence (the READ does not
complete).
Select List
The select list immediately follows the poll list in the address list. It contains one entry
for each address that may be selected (the number of entries minus the poll count).
0 = active, station is expecting data. If a READ is outstanding and the station is
selected, the READ completes with the first message from the supervisor
placed in the line buffer of the application process. A no error indication is
returned, the address-list entry number of the selected station is put in the
message control word, and the line is placed in the READ state.
1 = inactive, station is not expecting data. If a READ is outstanding and the station
is selected, Envoy responds with an RVI, WACK, or NAK as specified by the
polling type (the READ does not complete).
Example 5-2
is an example of an address list.