Envoy ACP/XF Application Programming Manual

EnvoyACP/XF and the Application Task
EnvoyACP/XF Application Programming Manual–132179
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Your Application and V.25 bis
Call Establishment
To establish a call for an automatic calling procedure, your application must direct the
EnvoyACP/XF (DTE) to perform these three functions.
If the modem connects the call, the modem raises the DSR to indicate the ending of V.25
bis mode and the beginning of data transfer mode. EnvoyACP/XF then issues ERROR
150, which signifies that the connection is successful. The modem also issues a VAL
message.
Therefore, your application should post a READ to look for ERROR 150. When
ERROR 150 is received, your application should remove the broadcast address (FF)
from the poll list by using a CHANGELIST procedure and begin data transfer in the
appropriate line protocol (SDLC or ADCCP-NRM).
Secondary SDLC Stations and Call Establishment
A secondary SDLC station cannot broadcast; a station must use the broadcast address to
communicate with the V.25 bis modem. However, you can circumvent this restriction as
follows:
•
Defining the station as primary temporarily.
•
Redefining the station as secondary after the call has been established.
Call Clearing
The modem is automatically reset to V.25 bis mode when the data transfer has been
completed under any of the following conditions:
•
DTR is dropped by the application (CONTROL).
•
The last opener of the line closes the line.
•
The line is disconnected by either party (DSR drop).
Call-Establishment Scenarios
The call-establishment process consists of communications between each station and its
own modem. The station establishing the call must have a configured V.25 bis-
compatible modem. The station receiving the call does not require a V.25 bis-compatible
Function Procedure
1. Ensure that the modem
(DCE) is available for
operation.
CONTROL 17, parameter 1
2. Provide the telephone
number.
WRITE a UI frame by setting bits 3 through 7 of the
MCW to zero, and sending CRNnnnnnnn in the
information block.
3. Decide to abandon the call. Retry?
Wait?
Try another number?