Northern UTA220/UTA220k - Manual (Page 75)

UTA220/UTA220k
11-1
Synchronous Operation
Chapter 11
Synchronous Operation
SYNCHRONOUS MODES
The UTA220 supports two synchronous modes. Operation in
each of these modes is described below.
Synchronous Mode 1: Sync Pause Mode
When a telephone connection is made, the UTA220 delays for 5
seconds (configurable with the S25 command ’0’) before
monitoring DTR.
This delay serves two purposes. If separate dialing and
communication terminals are used, this allows the terminal
operator to switch the EIA-232 cable between the two. If separate
dialing and communications software is being used on the same
terminal, the delay allows time for the dialing software to
complete and the communications software to initialize and turn
DTR on.
After the UTA220 connects, the DSR, CD, and CTS pins will be
high. This can be used by the DTE as an indication that it can
begin sending synchronous data to the UTA220.
The UTA220 disconnects if it detects an on-to-off transition of
the DTR pin when &D0 is not in effect, or it receives a disconnect
message from the switch. After a disconnect, the UTA220
returns to the off-line state. If the UTA220 is set to auto answer,
it will only answer when DTR is on or &D0 is in effect. If you
do not want the UTA220 to answer, DTR must remain low for
at least 8 seconds after the ringing ends.
Synchronous Mode 2: Dial Stored Number Mode
The UTA220 will automatically dial the telephone number
stored in directory entry number 0 when it detects and
off-to-on transition of the DTR pin.
Once the UTA220 connects, the DSR, CD, and CTS pins will be
high to indicate to the DTE that it can begin sending synchronous
data.
The UTA220 disconnects upon detecting an on-to-off transition
of the DTR pin when &D0 is not in effect, or receiving a
disconnect message from the switch. After disconnecting, the
UTA220 hangs up and returns to the
off-line state.
If the UTA220 is set to auto answer, it will only answer when
DTR is on or &D0 is in effect. If you do not want the UTA220
to answer, DTR must remain low for at least 8 seconds after the
ringing ends. After that time, DTR going high will cause the
UTA220 to originate a call. If DTR goes high during the ringing
process, but before the required ring count is reached, the
UTA220 will not originate a call.