Envoy ACP/XF Application Programming Manual

EnvoyACP/XF and the Application Task
EnvoyACP/XF Application Programming Manual–132179
1-16
Your Application and V.25 bis
modem; an auto-answer modem is sufficient. However, a V.25 bis modem allows the
receiving side to answer selectively or to reject incoming calls. Table 1-2 summarizes
the modem requirements.
When a station uses a V.25 bis-compatible modem for either call-establishment or call-
receiving, the station communicates with the modem through the broadcast address.
Table 1-3
shows the procedure calls to establish a call when the calling station and
receiving station each use a V.25 bis modem.
Table 1-2. Modem Requirements
Station Modem Optional/Required
Calling station V.25 bis-compatible Required
Receiving
station
V.25 bis-compatible Optional
Can answer selectively or reject incoming
calls
Other auto-answer modem Optional
Table 1-3. Establishing a Call With Two V.25 bis Modems
Calling Station
(with V.25 bis modem)
Receiving Station
(with V.25 bis modem)
FILE_OPEN_ line. FILE_OPEN_ line.
SETMODE 16—set line characteristics. SETMODE 16—set the line characteristics.
DEFINELIST—define address FF for
broadcast and specify other addresses as
required for the poll list.
DEFINELIST—define address FF for
broadcast and specify other addresses as
required for the poll list.
CONTROL 17 param 1—set DTR and wait
for DSR.*
CONTROL 17 param 1—set DTR and wait
for DSR.*
WRITE to station FF (modem), sending
CRNnnnnnnn (call request with number to
be dialed).
READ INC (incoming call from modem).
If the call is successfully connected, DCE
raises DSR.
WRITE CIC (connect incoming call) to
accept call, or
WRITE DIC (disregard incoming call) to
reject call.
READ status (ERROR 150) if the connect
was successful.
READ status (ERROR 150) if the connect
was successful.
READ VAL message from modem.
CHANGELIST—remove address FF from
the poll list.
CHANGELIST—remove address FF from
the poll list.
Proceed with communication—
CONTROL 13 (send SNRM or SABM).
Proceed with communication—
READ (for SNRM or SABM).
* The V.25 bis modem automatically transmits a special, local DSR to signal DTE to send a V.25 bis WRITE to
the local DCE.