AT&T AT&T manual Data Terminal Without Ascii Keyboard, Ascii Data Terminal With Keyboard, 107

and AB (Signal Ground) to function, while others require more RS-232 control signals to operate. An ADU (Figure 2-19) 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.

	TD				TO/FROM
TO/FROM	RD	ADU
	DTR				TN-726
RS-232C		(DATA
	DCD				DATA LINE
DTE		MODULE)
	DSR				CIRCUIT PACK
			(4-WIRE
	CTS
			CONNECTION	)

*CD CONTROL SIGNAL CONNECTED IN ADU TO PROVIDE CTS, DSR, AND DCD TO RS-232C

DEVICE

Figure 2-19. 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 (V2) feature.

b. ASCII Data Terminal With Keyboard

This category can be subdivided into two classes: (1) basic terminals, and ( 2 ) i n t e l l i g e n t , p r o g r a m m a b l e d a t a e q u i p m e n t s u c h a s p e r s o n a l computers. Basic terminals appear to the data port to be on-line and available whenever they are turned on, thus ready to enter either the

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