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Data Communications
Full-Duplex Operation
In a full-duplex environment, this terminal is capable of transmitting and receiving data
simultaneously. The ability to transmit may be inhibited temporarily, but it is never exclusive
of the ability to receive. Two physical sets of data lines are required. Control lines are needed
only when hardware handshaking or a modem is used.
When the terminal is connected to the host computer via a modem, the following primary
control lines are required:
Request to Send (RS/CA)
Clear to Send (CS/CB)
Data Terminal Ready (TRlCD)
Data Mode
(DMlCC)
Receiver Ready (RRlCF)
Pacing Mechanisms
In a full duplex environment, this terminal can participate in any of the following forms of
transmit pacing:
1. Hardware handshake. The host computer can temporarily restrain the terminal from
transmitting by:
a. Lowering the Clear to Send (CS/CB) line; or
b. Turning offSecondary Receiver Ready (SRRlSCF). Normally a low state is interpreted as
ttoff", but you can use the
SRR Inver t
field in the datacomm configuration menu to invert
the sense of the SRRISCF line so that a high state is interpreted as ttoff"; or
c. Lowering the Data Mode
(DMlCC)
line; or
d. All of the above simultaneously.
This type of transmit pacing can only be used in a hardwired configuration.
2. XON-XOFF handshake. The host computer uses the ASCII control codes XON «DCI» and
XOFF«DC2» to start and stop the terminal from transmitting. Note that a single XON
code cancels any number of preceding XOFF codes.
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