Dtr De-Assert; Handling Of Switching Between Data Call And Voice Call Mode - Beam RST100 Configuration Manual

If an incoming data call is received in voice mode and DTR remains high then the RST will
switch back to data mode to allow a connected application to answer the data call.
Default is 40s to allow for the ATD command.

DTR de-assert

The DTR De-assert sets how long to observe DTR is de-asserted on the Data port before we
switch back to normal voice mode. Allows time to quickly switch between two data
applications without reverting to voice mode and discarding the immediate AT set-up if
required. Default is 3 seconds.

Handling of switching between Data Call and Voice Call mode.

The RST100 has the capability to switch between Voice and Data Sessions, even when the
DTR signal is continuously being asserted by the Terminal program.
As a Data Session is started, the RST100 detects the assertion by the Terminal of the DTR
signal (Data Terminal Ready). The RST100 will then switch the Internal Satellite Modem
(ISM) to the Comm. Port (i.e. to the Data Session) if possible – switchover will be delayed if
there is a voice call in progress or the ISM is busy. At this time there is also a Data Activity
timer which starts, to detect whether the terminal data activity is ever absent for more than
the timeout setting "Timeouts
a busy tone will be heard if the phone is lifted. If this timeout expires the Comm. Port
relinquishes the hold of the ISM, and switches back to allow the Voice port access. When
the timeout expires, the Call LED is extinguished, and then a phone call then can be made
Consider the case where a Terminal is connected to the Comm. Port and the Data Activity
timeout expires. If then the Data Terminal sends more AT data, the RST100 detects the
data activity, and will switch back the ISM to the Comm. Port. During this short activity
detection phase, the initial data sent is purged, but subsequent Terminal data will be
transmitted to ISM as expected. Another way to re-activate the Comm. Port switch is by
disconnecting (thus de-asserting the DTR signal) the Comm. cable, or by closing down the
Terminal program.
The Data Activity timer is only in operation while the Data Session is in handshaking stage
(i.e. the sending of AT commands, dialling commands, and connecting commands). Once
the Data Session has connected to the remote Data Device (ISP, modem etc), then the DCD
line (or Carrier Detect) is asserted, and this remains in place until the session is ended.
While the DCD is asserted, the Activity timer is disabled and cannot affect the session. Once
the Session is ended and DCD is de-asserted (but the Terminal may still be connected), the
Data Activity timer will start again. Once this again expires the Call LED will extinguish, and
a Voice call can be made.
During a data session connected to the Comm. Port, and a disconnection is made, another
timer is activated ("Timeouts
from the ISM until the timer expires. This gives the user a chance to reconnect (within the
timer period) without dropping the data call if an accidental disconnect is made.
The DTR De-assert timer also allows programs to drop DTR for short periods (e.g. within 0 to
2 seconds) without losing access to, and current configuration of the ISM port.
The settings for the two timers mentioned can be configured in the Timeouts menu in
Supervisor Mode:
Timeouts Data RX
Timeouts DTR de-assert
RST-100 INSTALLATION AND CONFIGURATION MANUAL
Data RX" (default is 40 seconds). During this timeout period,
DTR de-assert"). The RST100 does not actually disconnect
Default = 40 seconds
Default = 2 seconds
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