Envoy ACP/XF Application Programming Manual

EnvoyACP/XF and the Application Task
EnvoyACP/XF Application Programming Manual–132179
1-17
Your Application and V.25 bis
Table 1-4 shows the procedure calls required to establish a call when the primary station
uses a V.25 bis modem and the secondary station uses a regular auto-answer modem.
Primary Station V.25 bis Generic Pseudocode Example
The following V.25 bis generic pseudocode example contains detailed procedure calls
for a primary station:
! Open the line "SDLC"
FILE_OPEN_ SDLC,fnum
! Get the current line setting.
SETMODE fnum,16,,,current_value !two words
! Set the line value for desired configuration.
SETMODE fnum,16,current_value[0],current_value[1]
! Define station "FF" and other needed stations
! Since you will be removing the broadcast address
! after the call is connected, it is more efficient to put
! the broadcast address at the end of your poll list.
DEFINELIST fnum,
[%HC100,0,0,0,%HC200,0,0,0,%HFF00,0,0,0],4,3,2,0
Table 1-4. Establishing a Call With Only One V.25 bis Modem
Calling Station
(with V.25 bis modem)
Receiving Station
(with regular auto-answer 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 the address required
for the poll list.
CONTROL 17 param 1—set DTR and wait
for DSR.*
CONTROL 11—set DTR and wait for DSR.
WRITE to station FF (modem), sending
CRNnnnnnnn (call request with number to
be dialed).
If the call is successfully connected, the
secondary modem raises DSR.
READ status (ERROR 150) if the connect is
successful.
READ VAL message from modem.**
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.
** READ status and READ VAL can occur in any order, and VAL may not occur at all. Requirements for the
response to a connection vary depending on the modem manufacturer’s implementation.