Envoy ACP/XF Application Programming Manual

EnvoyACP/XF and the Application Task
EnvoyACP/XF Application Programming Manual–132179
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Shutting Down a Data Link
operate efficiently when you use Two-way Simultaneous transmission (TWS). (See
Two-Way Alternate (TWA) Versus Two-Way Simultaneous (TWS) Operation on page 3-
10 for more information about using TWA and TWS.)
Shutting Down a Data Link
An application normally shuts down the data link by using the CONTROL 18 procedure
to send a DISC command. See Section 2, Asynchronous Balanced Mode (ABM)
Protocols, for information about using the DISC command with the Asynchronous
Balanced Mode. See Section 3, Normal Response Mode (NRM) Protocols, for
information about using the DISC command with Normal Response Mode.
When using switched-line facilities, you may want to disconnect the line after
disconnecting any stations. Your application can do this by using a CONTROL 19 call to
clear the Data Terminal Ready modem signal.
Closing a Line
When an application finishes using a communications line, it should issue one CLOSE
call for each FILE_OPEN_ call.
Recovering From Errors
Your application can encounter different types of errors: application errors, protocol
errors, EnvoyACP/XF internal errors, errors requiring operator intervention, and path
errors. Your application principally is responsible for handling application errors and
protocol errors.
The file-system error codes returned for EnvoyACP/XF are summarized in Appendix A,
“Summary of Errors.”