Instruction manual

FEATURES AND SERVICES
The following describes the categories and attributes of each:
1. DTE Devices
This group of data endpoints have one thing in common: their interface configuration
(although RS-232 control signal utilization varies significantly from terminal to
terminal). Some data equipment do not use any RS-232 control signals; these
require only BA (Transmitted Data Ready-Tx), BB (Received Data Ready-Rx) and AB
(Signal Ground) to function,
while others require more RS-232 control signals to
operate. An ADU (Figure 2-21) can send Data Terminal Ready (DTR) from the data
terminal to the Data Line circuit and the Data Line circuit can send a control signal to
the data terminal. The signals Data Set Ready (DSR), Clear To Send (CTS), and
Received Line Signal Detector (DCD) are all connected to the control signal from the
DLC in the ADU and available if required by the data terminal. Refer to Section 5
(Port Specifications) for additional information.
TO/FROM
RS-232C
DTE
TD
RD
ADU
TO/FROM
DTR
(DATA
TN-726
DCD
MODULE)
DATA LINE
DSR
CIRCUIT PACK
CTS
(4-WIRE
CONNECTION)
* CD CONTROL SIGNAL CONNECTED
IN ADU TO PROVIDE CTS,
DSR, AND DCD TO RS-232C
DEVICE
Figure 2-21. Asynchronous Data Unit Interface Signals
The following categories are part of the DTE data endpoint group:
a.
Data Terminal Without ASCII Keyboard
This category includes such devices as Fax machines, EBCDIC or Baudot
terminals, and receive only devices such as printers.
Once connected to an ADU and turned on, these data endpoints appear on-
line, available, and ready to enter the Setup mode on auto-answered calls
(modes are described below).
These endpoints will display or print
information received after a valid connection has been established without
additional RS-232 control from that endpoint.
Note that since these
endpoints cannot establish calls for themselves, they must either be called by
other endpoints or have calls established for them via the Transfer to Data or
Third-Party Call Setup feature.
2-130