This
section
is applicable
to many
acoustic couplers and modems which
carry out asynchronous communications at rates of 1200 baud or less.
It is
almost
always
applicable
for asynchronous couplers and modems operating at
300 baud or less.
Specifically,
it is applicable
to modems
and couplers
which
require
only
three
RS-232C
lines coming from the computer: Transmit
Data (line 2), Receive Data
(line 3), and Signal Ground
(line 7).
Because the Bitstreamer
II board
is wired
for direct
connection
to a
terminal, you cannot simply connect the Bitstreamer II serial
I/O cable
to
the modem.
This
is because
both
the modem and the Bitstreamer II serial
channels in their normal configuration are Data Communication Equipment, and
therefore they bot.l1expect to receive data on line 2 and to transmit data on
line 3.
Another
problem
is that most
modems
and couplers
have
female
SOCkets, and the 03-25 connector at ~~e end of the Bitstre~ner II serial I/O
cable is also a female socket.
One
solution:
create
a three
line cable with male D8-25 connectors at
both ends.
Wire line 7 straight across, and cross lines 2 and 3.
In other
words, connect pin 2 of one connector to pin 3 of the other, and vica versa.
Such a cable will work with any modem or coupler requiring only three lines.
Connect
one end of the cable to the 08-25 of the Bitstre~ner II Serial I/O
cable and ~~e other end to the m::>dem
or coupler.
Another solution: order a "Null Hodem Cable" from Vector Graphic, or make
one yourself.
This is a very short
cable with
a male
08-25
connector
at
both
ends.
Lines
2 and 3 are crossed
(as well as other pairs of lines not
relevent here).
Plug one end of this cable into the 00-25 at the end of the
Bi tstreamer
II Serial
I/O cable
and plug
the other
one
into thef~'Mle
connector at ~,e end of an RS-232C extender cable coming from
the modem
or
coupler.
We strongly
suggest
that you do not modi fy the 8i tstreame r I I board
itself or the Bitstre~ner II Serial I/O cable, in order to cross lines 2 and
3.
By modifying or adapting
the external
cabling
instead,
the computer
itself
remains
standard,
and the serial
channels
can easily be used for
connecting to a terminal or other kind of peripheral if every required.
Summary of Contents for Bitstreamer II
Page 1: ...lit t tiCAli1iC I JI U E I mAnUAL...
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Page 3: ...BITSTREAMER II BOARD Revision 1 USER S MANUAL Revision A January 1 1980...
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