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Chapter 6. Configuration
52
ISU 2x64 Dual Port ISDN Service Unit User Manual 61200051L1-1D
DTR Options
Ignore DTR causes the ISU 2x64 to disregard the state of the data
terminal ready (DTR) pin. Cmd when Off forces the unit into the
AT command processor mode when DTR is not asserted. To
return online, DTR must be asserted, followed by the AT0 com-
mand. Idle when Off forces the unit to end the current call when
DTR is no longer asserted. Off>On dial #0 allows one call
attempt to be automatically established when the DTR signal
goes from inactive to active. While DTR is active, front panel
dialing is also possible. When DTR goes inactive, any outgoing
call present is disconnected. Off>On dial #0 uses the phone
number in stored number register 0 to establish the call. To store
a number for automatic dialing, see the section Front Panel Dialing
Options. Dial #0 if On allows calls to be automatically estab-
lished when the signal is in the active state. The unit attempts to
establish a call using SN0 until the call is established or DTR goes
inactive. Answer if On only allows the unit to answer an incom-
ing call if DTR is asserted.
DSR Options
DSR forced on causes the data set ready (DSR) signal on the DTE
connector to always be asserted. Off Idle+Test causes the DSR to
be disasserted if the ISU 2x64 is in test or there is not an active
call. Off Link Down causes the DSR signal to be disasserted
when the ISDN interface is not ready.
Flow Control (asynchronous data format)
Selecting Hardware Flow (see Figure 6-18) allows the ISU 2x64
received data to be presented to the DTE interface only when RTS
(request to send) is asserted and allows DTE transmit data to be
presented to the 2x64 when CTS is asserted. Software Flow con-
trol uses XON/XOFF inband to control data transferred between
the DTE and the ISU 2x64. Selecting No Flow Ctrl disables flow
control. Either Hardware of Software flow control should be used
when asynchronous BONDING or DTE rates higher than the
effective loop rate are used (i.e., 115.2 kbps over 112 kbps loop
rate).