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Line Descriptions
Line (CCITT 108.1) can be used only with Line Set lD because circuit CE/125 is
required to use this option.
uspecial-These circuits are not defined by RS-232C or CCITT V.24.
STD signals are those signals that the line set always presents to or expects to
receive from the external modem or autocall unit.
OPT signals are those signals that the line set is capable of presenting to or
receiving from the external modem or autocall unit, but whose use depends upon
the type of modem, communication facility, program support, etc., used.
NI
A are those signals not available on the line set.
Transmitted Data (BA/103). This circuit transfers data from the IBM 3704 and
3705 to the modem for transmission on the communication channel. The IBM
3704 and 3705 holds circuit BA/103 in the Mark condition when no signals are to
be transmitted, or when any of the following circuits is in an OFF condition:
Request to Send
Clear to Send
Data Set Ready
Data Terminal Ready
CA/105
CB/106
CC/107
CD/108
Received Data (BB/104). The modem generates signals on this circuit in re-
sponse to data signals received from the communication channel.
Request to Send (CA/105). The IBM 3704 and 3705 generate signals on this
circuit to condition the local modem for data transmission and, on a half-duplex
channel, to control the direction of data transmission of the local modem.
Clear to Send (CB/106). The modem must present signals on this circuit to the
IBM 3704 and 3705, indicating whether or not the modem is ready to transmit
data.
The ON condition, together with the ON condition on interchange circuits
CA/105, CC/107, and CD/108, indicates to the IBM 3704 and 3705 that signals
presented on circuit BA/ 103 (Transmitted Data)
will
be transmitted to the
communication channel.
The ON condition of circuit CB/106 is a response to a concurrent ON condition
of circuit CC/107 (Data Set Ready) and circuit CA/105 (Request to Send),
delayed as may be appropriate to the modem. This delay
is
used to establish a
data communication channel to remote data equipment, and include• the removal
of the MARK HOLD clamp from the Received Data interchange circuit of tlte
remote modem.
Data Set Ready (CC/107). The modem generates signals on this circuit to
indicate its status.
The ON condition on this circuit must be presented to the IBM 3704 and 3705
when:
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IBM 3704 and 3705 Communications Controllers Original Equipment Manufacturers' Information
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