Envoy ACP/XF Application Programming Manual

Normal Response Mode (NRM) Protocols
EnvoyACP/XF Application Programming Manual–132179
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NRM Application Process Interface
NRM Application Process Interface
The application process controlling an EnvoyACP/XF SDLC or ADCCP-NRM station
interacts with the data link through:
•
Calls to Guardian file-system procedures
•
Condition codes (CCE, CCG, and CCL) returned by the procedures and numerical
error codes returned by the FILEINFO procedure
•
Application-level data transferred through I-frames and U-frames
This section describes considerations particular to NRM.
Section 4, System Procedure Call Specifics for EnvoyACP/XF
, summarizes the Guardian
file-system procedures for EnvoyACP/XF, and Appendix A, File-System Errors,
summarizes the EnvoyACP/XF error codes.
Opening a Line
The application first must open the communications line by calling the OPEN
procedure.
Be aware of the following restrictions on exclusive access:
•
Multiple OPEN calls require that access be shared.
•
If a line is opened for exclusive access, it should be opened only once.
•
The only other user process that can open the same line concurrently is the particular
application’s backup process.
The line is opened with the number of concurrent pending nowait I/O operations set
between 0 and 15. Unless you must use a different value, use the value 15.
Setting Line Capability Characteristics
The application issues one or more SETMODE procedure calls to ensure that certain
line characteristics are set. These characteristics are:
•
Primary or secondary station
•
Address field
•
Control field
•
Polling interval
•
Retry timer
•
Number of retries
•
Two-way Alternate (TWA) or Two-way Simultaneous transmission (TWS)
•
Full-duplex or half-duplex communications