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
4-23
Normal Text
•
Intermediate Text Blocks on page 4-23
Normal Text
Normal text is indicated by messages having the following form:
message = STX—text—ETB
message = STX—text—ETX
(message length = 2 + text length)
Transparent Text
Transparent text is indicated by messages having the following form:
message = DLE STX—text—ETB
message = DLE STX—text—ETX
(message length = 3 + text length)
Transparent mode is initiated by inserting a DLE control character before the STX.
Transparent text, including data-link control characters, continues being sent until an
ETB or an ETX is sent and is followed by nothing else. The transmission of DLE text
characters is handled entirely by Envoy hardware. Envoy automatically inserts a DLE
character in front of a DLE text character upon transmission and deletes a DLE
character in front of a DLE text character upon reception. The application process deals
only with the original binary text.
Headings
Headings use the formats shown in Table 4-7.
Intermediate Text Blocks
The BISYNC protocol allows a message to be divided into segments called intermediate
text blocks (ITBs). This division causes a single message to be transmitted as a series of
intermediate messages, each of which has its own block -check character. Each block is
checked for errors when received and the entire message is acknowledged only when the
last intermediate block is received (that is, after an ETB or an ETX). Intermediate text
blocking allows individual (or intermediate) blocks to be checked for errors and allows
Table 4-7. Header Formats
Header Type Format
Heading only message = SOH-heading-ETB
(message length = 2 + heading length)
Heading and normal text message = SOH-heading-STX-text-ETB
message = SOH-heading-STX-text-ETX
(message length = 3 + heading length + text length)
Heading and transparent text message = SOH-heading-DLE STX-text-ETB
message = SOH-heading-DLE STX-text-ETX
(message length = 4 + heading length + text length)