US Robotics COURIER - CHAPTER 4. INTERFACE CONTROLS-ASYNCHRONOUS OPERATIONS

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COURIER HIGH SPEED MODEMS
CHAPTER 4. INTERFACE
CONTROLS-
ASYNCHRONOUS OPERATIONS
Use the commands explained in this chapter to select modem
settings at the terminal or computer and phone link interfaces.
These
settings apply only to asynchronous operations. For syn-
chronous calls, see Chapter 7.
TERMINOLOGY
ARQ (automatic repeat request, or retransmission) is the term
used by USRobotics in error control commands and response
codes. An ARQ connection indicates a call under error control.
The
terminal or computer is referred to as the DTE (Data Termi-
nal Equipment). The DTE rate is the rate at which your DTE and
Courier modem communicate, for example, 19.2K bps. The
Courier modem is referred to as the DCE (Data Communications
Equipment).
Figure 4.1 indicates which commands control modem operations
at the DTE/DCE (computer-to-modem) and phone link
(modem-to-modem) interfaces.
DTE
Local
DTE
Interface
RS-232
DCE
Link
Interface
Phone Link
DCE
Remote
DTE
Interface
RS-232
r-----i DTE
DTE Interface
Flow Control
Link Interface
V.32/HST mode: Bn
Transmit Data: &Hn
Received Data:
&Rn, &In
DTE rate: &Bn
CD operations: &Cn
DTR operations: &Dn
DSR operations: &Sn
Error Control (ARO): &Mn
Data Compression: &Kn
Link rate: &Nn
Figure 4.1-lnterface Control Commands
Detailed command descriptions are in this chapter. If you're
familiar with modem operations, you may want to review the
Quick-Start instructions in Chapter 3 instead.
Interface Controls 4-1