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EIA-366 Dialer Operation
Abandon Call and Retry (ACR)
EXAMPLE DIAL SEQUENCE
7-4
ACR is supplied by the dialer to indicate that the call cannot
be successfully established. The on condition instructs the
DTE to abandon the call by dropping the call later. ACR
remains on until CRQ is turned off.
The following is an example of the sequence of events that
occur when a call is initiated using the EIA-366A dialer port.
• Data Line Occupied (DLO) must be off for the dial sequence
to begin.
• The DTE turns on Call Request (CRQ) to initiate dialing.
• When CRQ is turned on, the dialer port turns on DLO to
indicate that the data port is now in use. The dialer turns on
Present Next Digit (PND) to request a dial digit from the
DTE.
• The DTE sets the digit signal circuit bits (NB1, NB2, NB4,
and NB8) to the correct value for the first dial digit, then turns
on Digit Present (DPR).
• When DPR turns on, the dialer reads the digit and responds
with another PND.
• The PND/DPR sequence continues until either EON is
received or five seconds expires without receiving another
digit (DPR is not turned on to present another digit).
• When all the digits are received, the dialer initiates the call
on the data port to which the dialer is dedicated.
• When the call is connected, Distant Station Connected (DSC)
is turned on by the dialer port. If the call cannot complete
successfully, Abandon Call and Retry (ACR) is turned on
until CRQ is turned off.
• The call can be terminated before the call is connected by
turning CRQ off.
• Once the call is completed, the call can be terminated by
normal disconnect methods such as disconnect by the switch,
the front panel, or DTR disconnect.
UTA220/UTA220k
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