Communications Data Set Eia Interface; Serial I/O Device Eia Interface 2·11 - IBM 5100 Maintenance Information Manual

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COMMUNICATIONS DATA SET EIA INTERFACE
The data set interface between the expansion feature card
and the data set is the EIA RS232C/CCITT V.24-V.28
standard interface and is connected as shown in the follow-
ing diagram:
Base I/O Expansion
Card (F2) Bus Out
...
Feature
......
Card
.....
Bus In (B2)
...
Device Adr Bus
... ...
Control
'+ext horiz dr'
(from display card)
The output EIA lines are turned on, and the input EIA
lines are sensed, by the communications I/O microprogram.
An on signal on an EIA control line is indicated by a plus
voltage level of +3.0 to +25.0V. An off signal is indicated
by a minus voltage level of -3.0 to -25.0V.
The function of each EIA line and the sequence in which
they are turned on or sensed during communications is:
If the 5100 is going to transmit data:
1.
2.
3.
4.
5.
The 5100 turns on data terminal ready to indicate
that it is ready to communicate.
The data set turns on data set ready to indicate that
it is ready to communicate.
The 5100 turns on request to send to indicate that
it is ready to send data to the data set.
The data set turns on clear to send to indicate that it
is ready to send data to the remote system.
The 5100 sends the data to the data set on the trans-
mitted data line. (See Data Format in Theory of
Operation .)
line Name
Data Terminal Ready
Request to Send
Transmitted Data
Received Data
Clear to Send
Data Set Ready
Signal Ground
Protective Ground
If the 5100 is going to receive data:
Pin
No
20
4
2
3
5
6
7
1
Data
Set
1. Data terminal ready and data set ready are turned on
as in a transmit operation.
2. Clear to send and request to send are not used.
3. The 5100 receives the data from the data set on the
received data line. (See Data Format.)
Signal ground provides a common ground for all circuits.
Protective ground is connected to the frame of the 5100.
Refer to the IBM 5100 Maintenance Information Manual,
for the communications connector and expansion feature
card pin numbers.
SERIAL I/O DEVICE EIA INTERFACE
The 5100 uses the EIA RS232C/CCITT V.24·V.28 standard
interface to connect the I/O devices used with the Serial
I/O Adapter feature.
The EIA lines on the expansion feature card are turned on
(output lines) and sensed (input lines) by the serial I/O
input/output microprogram. The control lines are at a
plus voltage level when active (on) and a minus voltage
level when inactive (off). The acceptable voltage levels
are +3.0 to +25.0V for an on level and -3.0 to -25.0V
for an off level. For the voltage levels and the format of
the data on the data lines (transmitted data and received
data), see Data Format.
Theory Of Operation 2·11