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
4-17
Polling Type
The supervisor polls each station a maximum of ten times for each call to the READ
procedure when the line is in the CONTROL state. If polling is in progress, the change
does not take effect until the next call to READ.
Specific Polling
Specific polling occurs when a designated station is polled once. Polling of only one
specified station is designated with a call to the CONTROL procedure. CONTROL 13
(send EOT and enable specific poll) is indicated by setting the control parameter.<0> to
1. Control parameter.<8:15 > specifies the entry number of the station in the address list
to be polled.
The specific poll takes place the next time you call the READ procedure. Table 4-6
shows a station's possible response to a poll and what occurs as a result.
Following a specific poll, subsequent polling reverts to the currently specified polling
type (that is, continuous or noncontinuous).
Example 4-5
shows specific polling, using the example address list presented in
Example 4-2.
Station BB01, the first entry in the address list, is polled once. If the station responds
with a message, the READ completes with the message in the line buffer, the line in the
READ state, and a CCE indication. If the station responds with an EOT sequence, the
READ completes with the line in the CONTROL state and an error 176 (poll sequence
ended with no responder).
Table 4-6. Possible Responses to a Poll
Response from the Polled Station Resultant Line State Error Information
Responds with a message Line in the READ state Error 0.
Responds with an EOT sequence Line in the CONTROL
state
Error 176 (poll sequence
ended with no responder).
Fails to respond or an incorrect
response is received
Error indication The entry number of the
erring station is returned
in the message control
word (MCW)
Example 4-5. Specific Polling
CALL CONTROL (linefnum, 13, %100001);
IF < THEN ...
CALL READ (linefnum,linebuf,...);
IF < THEN ...