IBM Series 1 User Manual page 155

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The
teletypewriter adapter card generates the current for the
transmit and receive loops. The following table shows
connections at the card, the customer access panel (CAP),
and the device.
Teletypewriter
card connector
B1 Non-isolated contact in
A3 Non-isolated contact in
+
B5 signal ground (transmit -)
A2 Current driver, current=mark
CAP Device
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3
Transmit +
4 Transmit -
1
Receive
+
2 Receive -
No external power supplies are required in this
configuration. Current for the transmit and receive current
loops is supplied by the teletypewriter adapter card. The
teletypewriter adapter card to OEM device cable for this
configuration is just a straight cable without any series
power supplies (Figure 4-10).
Note that in this configuration, the transmit and
receive loops are not isolated, since both loops are driven
with voltages referenced to logic ground. This
configuration puts 12 volts across the receive input and 24
volts across the transmit output of the attached device.
Teletype Models ASH 33, ASH 35, and KSR 33 require 24 volts
across their transmit output for reliable operation.
For devices that require only 12 volts across their
transmit output, pin
B05
should be used instead of
B01
at
the connector on the teletypewriter adapter caLd.
Note. The 12 volt power jumper on the teletypewriter- adapter
card must be installed for this configuration (refer to
Figures 4-5 and 4-7).
4-32 GA34-0033