Northern UTA220/UTA220k manual Chapter Synchronous Operation, Synchronous Modes

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.

UTA220/UTA220k 11-1