55
BOCA PRO16 Reference Guide
Character echo and response codes should not be selected when syn-
chronous communications are used. Use the E0 and Q1 commands to
disable character echo and response codes.
As soon as your modem has completed dialing it will examine the state
of the DTR signal. If DTR is asserted your modem will go on line in
synchronous mode, otherwise the modem will hang up and return to
asynchronous local command state.
FData should only be transmitted once DCD, DTR and CTS have been
asserted. Your computer should not assume that if CTS is asserted then
it is safe to begin transmitting data — your modem will keep CTS
asserted whenever it is in local command state.
Hanging Up
Your modem will hang up and return to asynchronous mode if carrier
is lost for longer than the period defined by S Register 10 or if DTR is
lowered after the &D2 command has been issued.
Answering Calls
To automatically answer incoming calls, S Register 0 must be set to a
non-zero value (as with asynchronous auto-answering). Once a call has
been answered there is no means of returning to asynchronous mode
apart from hanging up the modem. This will occur if the carrier is lost
for a period in excess of the time defined by S Register 0 or if DTR is
lowered after the &D2 command has been issued.
Synchronous Mode 2
Synchronous mode 2 is specifically designed for use with dedicated
synchronous terminals. The phone number to be dialed is stored in the
modem, the synchronous terminal causing the modem to dial by assert-
ing the DTR signal.
When the terminal asserts the DTR signal (DTR makes an OFF-ON
transition), your modem will dial stored phone number zero. The phone
number may contain dial modifiers. See the Command Descriptions
chapter of this guide for details on the &Z command.
Before connecting your modem to your synchronous terminal, the
modem must first be configured using an asynchronous terminal or
computer.
Synchronous Modes
Synchronous
Modes
pro16ref.pm6 6/14/96, 2:37 PM55
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