Vector Graphic Bitstreamer II User Manual - page 39
Serial
Channel C can be used for
20 mAcurrent
loo~ COffinlW1icationra~1er
than RS-232C.
To convert
it,
install
a jumper connecting
pad 1 and pad 2 in
area
G,
found about
2 inches
from the upper
right-hand
corner
of ~1e board.
The current
loop inputs
and outputs
are then
connected
to
four
of
the
six
pins
of the molex coru1ector
J6,
in the upper right-hand
corner
of the board.
Use only the
first
four
pins
from left
to right.
They have
the
following
functions
from left
to right:
+
IN, - IN,
+
OUT, - OUT.
Before
using
this
section,
read
over
Sections
1.5, 1.9,
and
1.10
in
Perspective.
The three
8251
TxRDYpins,
the
three
8251
RxRDYpins,
and ~he
55
Hz real
time clock
are accessed
in jumper area A, as listed
below:
(Mask bit
will
be
explained
later.)
Interrupt
Source
Pad in Area A
Mask Bit
Serial
ChanneI A TxRDY
3
0
Serial
Channel A RxRDY
6
1
Serial
Channe
1
B T". 7 2 Serial Channel B RxRDY 4 3 Serial Channe 1 C TxRDY 2 4 Serial Channel C RxRDY 5 5 55 Hz Real Time Clock 1 6 PINT 8 To cause one of the TxRDY, RxRDY,or real time clock lines to interrupt the processor, install a jumper bet:..,.een the appropr ia te pad in a raa A and pad 8 in area A. Pad 8 runs directly to the PI~T line of G~e 5-100 DjS. To cause mre wan one TxRDY and/or RxRDY line to interrupt the processor, simply tie all desired pads toge~1er in area A and then tie them to pad 8. (For readers r.i1o understand digital electronics, this can be done because the 8251 interrupt sources are connected to area A via open collector gates. ) However, you C~~NOT tie the real time clock to pad A-a in combination wi th the 8251 interrupt sources. If you want to use the real time clock as