Async Terminal Operatio ns A-3
D or P – is the letter “D” or “P” (if P, the data will not be echoed locally),
data – is the user data.
An example of a Call Requ est to call ed address 1000000000 with the Reverse Charging
facility plus user data “abcde” is: R-1000000000Dabcde
An Abbreviated Address can be substituted fo r the complete called address
if no facilities are included. Also, X.28 convention demands that when
sending a Call Request packet using an abbreviated address, you precede
the address with a period. If you want to add user data to the packet, you
must separate it from the abbreviated address with an asterisk. The format
is: .address*data
If the Call Request is successful, the async PAD will receive a Call Accept packet
from the device at the other end of the call. Connection is now established, and the
terminal will display COM. If the Call Request fails, the terminal will display a diag-
nostic message explaining why. The various messages are some of the PAD service
signals described late r in this ap pendix.
To se nd data o nce yo u are in Data Transfer mode, simply enter the da ta. To cl ear a call,
enter Command mode an d t ype clr [Enter]. The async terminal will display: CLR conf.
Async PAD Service Signals
Transmission of PAD service signals is determined by async PAD profile
paramet er 6.
* (Asterisk) – is normally the PAD prompt character.
“nnnnn ” COM – means that a vitual circuit has been established with a subscriber
whose ID is “nnnnn.”
ALREA DY C O NNECTE D – indicat es there is al ready a VC set up, so an other call can no t
be made until the current call is cleared.
AUTOC AL L INITI ATED BY SUB S CRIBER “nnnmm” – is self-explanatory.
AUTOCA LL RETRI ES EXHAU STED- RE T URN TO COM MAND ST AT E – means that the
autocall retry timer has expired.
CALL CL EARED – indicates that the call is being cleared.
CALL TIMED OUT – is di splaye d when the ne twork does n ot resp ond to a virt ual cir cuit
call setup request within a certain time.
CLR (cause) (cause code) (diagnostic code) – is displayed when the call is cleared.
Some common causes and codes are listed in Appendix B.
CLR CON F – confirms the clearing of a call.
DISCONNECT TIMER EXPIRED – indicates that the inactivity timer on the port has
expired.