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
4-6
Timeouts
•
Set a retry count value for each line when issuing the ADD DEVICE command
(RETRIES modifier).
•
Alter the retry count value using the SETMODE 15 procedure. If an error condition
persists after the operation has been retried the specified times, Envoy returns an
error indication to the application process that requested the operation.
Timeouts
The protocol uses timeouts to detect error conditions. You can designate a timeout value
in either of the following ways:
•
Specify the desired value for the TIMEOUT modifier when issuing the ADD
DEVICE command.
•
Call the SETMODE 15 procedure.
Envoy support for timeouts and retries is summarized in Table 4-2
.
Table 4-3
summarizes the effect of the timeout value during the WRITE and READ
procedures.
Accommodating Message Processing Time
Envoy retries an operation that times out the number of times specified by the retry
count before an error indication is returned to the application process. An application
process acting as a multipoint supervisor station does not acknowledge a message
received in one call to the READ procedure until there is a subsequent call to the READ
Note. To conform to the BISYNC protocol, the timeout value must be greater than 2.6 sec-
onds. You should not specify a smaller value. (The default value when issuing the ADD
DEVICE command is 2.7 seconds.)
Table 4-2. Timeout and Retries
Feature Default Value SYSGEN Modifier SETMODE Procedure
Timeout 2.7 seconds TIMEOUT SETMODE 15, param 1
Retry Count 3 RETRIES SETMODE 15, param 2
Table 4-3. Effect of Timeout Value
Protocol State Effect of Timeout Value
During a WRITE Determines the period of time Envoy waits for an acknowledgment
from the tributary station.
During a READ Determines the period of time Envoy waits for an acknowledgment
from a polled tributary station,
or
the period of time Envoy waits for a message from a tributary station
that has responded to polling.