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Multiplexer
Data Set
Data Set
DataSet
or line
or line
or Line
Adopter
Adapter
Adapter
2740
2740
2740
Figure 21. l\lultipoint-Multiplexer Type
IBM 2741 CONFIGURATIONS
The IBM 2741 Communication Terminal can only be
connected point-to-point to the multiplexer of a re-
mote computer. See Figure 22. . The terminal can
transmit to a computer, such as the IBM System/
360, by means of a 2701 Data Adapter Unit, a 2702 or
2703 Transmission Control, or a 2712 Remote Multi-
plexer.
2740 TIMING CONSIDERATIONS
The following timings are based on a wide variety of
system configurations and applications. These tim-
ings will vary for specific applications.
Timeout Conditions
The IBM 2740 Communications Terminal will time-
out when any of the following conditions exist:
• No Data has been transmitted over the line for an
interval of 1'; seconds by a terminal in transmit
mode (with the Station Control feature installed).
The terminal will return to a standby mode "and
no code will be tr8.ll8mi tted.
• No data has been transmitted over the line for an
interval of 15 seconds by a terminal in transmit·
mode (with the Transmit Control feature installed).
If
the transmit control switch is set to the MTC
poSition, the terminal reverts to standby status
Data Set
or line
Adopter
CPU
Multiplexer
Channel
Data Set
or Une
Adapter
Figure 22. IBM 2741 Point-to-Point
and no EOT
@
code is transmitted. If the trans-
mit control switch is set to the OFF position, an
EOT
@
code is transmitted and the terminal re-
verts to a standby status •
• If
the Dial-Up feature is used and the line connec-
tion is lost, the terminal returns to standby status.
If
the Dial-Up feature is used and the terminal has
the Transmit Control feature installeci. loss of the
line connection for a period· of 15 seconds causes
the terminal to disconnect from the line and no
code is transmitted.
Delay Conditions
When power is first turned on, the terminal requires
a delay of one second in order to reset the various
circuits to home positions.
If
Limited-Distance Type
2, Leased Line or Shared Line, Line Adapters are
used by the terminal, an additional delay of six sec -
onds is required.
If
the Station Control feature is
installed, an additional delay of 15 seconds is re-
quired. This delay follows the six-second delay,
if
both features are installed (Line Ada pter and Station
Control).
Following the delay(s), the terminal is switched to
a standby status with only the control circuits active.
The keyboard is locked and the typewriter motor is
not running. When the terminal switches to a trans-
mit status, a delay of one second allows the type-
writer motor to attain full speed.
Typewriter Delay Conditions
The following formula is used to calculate the elapsed
time in milliseconds when the typewriter is perform-
ing a carrier return and line feed operation (CR/LF),
or a tabulate" (tab) operation:
(1.
5
+
T) x67. 5 ;;;; elapsed time in milliseconds .
T
=
number of inches of carrier travel.
The number of idle codes required for each mechani-
cal operation is as follows, where N is the number of
codes required and T is the number of inches of
Data Set
or line
2741
Adopter
Data Set
or line
2741
Adapter
19
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