IBM 1 Series - Page 137

Current Loop Without User’s Power Supplies
4-32 GA34-0033
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:
Series/1 TTY CAP Device
card connector pin connector
BI Nonisolated contact in — 3 Transmit —
A3 Nonisolated contact in + 4 Transmit +
B5 Signal ground (transmit —) 1 Receive —
A2 Current driver, current=mark 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 a straight cable without any series power supplies (Figure
4-10).
In this configuration, the transmit and receive loops are not isolated,
because 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 ASR
33, ASR 35, and KSR 33 require 24 volts across their transmit outputs for
reliable operation.
For devices that require only 12 volts across their transmit outputs, pin
BOS5 should be used instead of BO1 at the connector on the teletypewriter
adapter card.
Note: The 12-volt power jumper on the teletypewriter adapter card must
be installed for this configuration (refer to Figures 4-2 and 4-7).
Connections for current loop when teletypewriter adapter supplies current
* Inverted signal
(current = space)
is available on B3.
from ASR 33 wiring diagram
ASR 35 cable connections
from ASR 35 schematic
I |
Telety pewriter adapter | Bee I/O device
in
| | ASR ASR
| | 33 35
Current driver, current a9 r | |
=
mark*
O
ransmit
+
:
2
l
O
Receive
+
X7
T7
BS , we
Signal ground O Transmit ' | , 4) Receive — X6 T8
|
A | |
Nonisolated contact in + | Receive + | 4 | +i
©- i i —O Transmit + X3 TS
Bl ae
Nonisolated contact in-— ©- Receive | 3 | —© Transmit — x4 T6
(or) BS
(BS for 12 volts) \ ,
(B1 for 24 volts
ASR 33 cable connections
Figure 4-10. Connections for current loop when the teletypewriter adapter supplies current
for the loop