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
ADM-2 Multipoint Supervisor Protocol
Envoy Application Programming Manual—427159-001
7-14
Polling Type
Each terminal is polled a maximum of ten times for each call to the READ procedure
when the line is in the CONTROL state (if polling is currently in progress, the change
does not take effect until the next call to READ).
Specific Polling
Specific polling occurs when a designated terminal is polled once. The polling of only
one specified terminal is designated with a call to the CONTROL procedure. The
CONTROL operation is 13 (send EOT) and specific polling is enabled by setting control
parameter.<0> to 1. Control parameter.<8:15 > specifies the entry number of the
terminal in the address list that is to be polled.
The specific poll actually takes place the next time the READ procedure is called.
Possible responses to a specific poll are as follows:
•
If the terminal responds to the poll with a message, the READ completes with an
error 0 (operation successful).
•
If the station responds with an EOT sequence, the READ completes with an error
176 (poll sequence ended with no responder).
•
If the polled terminal fails to respond to the poll or if an incorrect response is
received, the READ completes with an error indication; the entry number of the
terminal in error is returned in the message control word.
Following a specific poll, subsequent polling reverts to the regular, current polling type
(that is, continuous or noncontinuous). The following example shows specific polling,
using the sample address list presented earlier under Address-List Format
on page 7-8.
Terminal "22p," the first entry in the address list, is polled one time. If the terminal
responds with a message, the READ completes with the message in linebuf and a CCE
indication, and an ACK is transmitted with the next READ as regular polling resumes.
If the terminal responds with an EOT sequence, the READ completes with an error 171
(no response or invalid response received).
Example 7-5. Specific Polling
CALL CONTROL (linefnum, 13, %100001);
IF < THEN ...
CALL READ (linefnum,linebuf,...);
IF < THEN ...
Note. Specific polling is intended to be used only once before resuming regular polling. If an
attempt is made to do two specific polls in a row, ACK is not sent to acknowledge the receipt of
data from the first poll.