IOD-72
Digital Input/Output Card
FEATURES
- 72
channels of TTL digital I/O lines
- All
I/O lines buffered by tristate transceivers. Outputs
sink 24mA and source 15mA
- Four-
and eight-bit groups independently selectable for I/O
- Pull-up
resistors to provide CMOS and contact closure compatibility
- Cable
crosstalk suppression by grounds on all even-numbered
conductors
- 50-pin
connector for compatibility with Western Reserve Controls,
Opto-22, Gordos, Potter and Brumfield, etc.
-
External
interrupts
FUNCTIONAL
DESCRIPTION
These
are 24-, 72-, and 120-bit half-size, 3/4-size, and full-size
cards respectively. A Programmable Peripheral Interface
chip, type 8255-5 provides three 8-bit ports (A, B, and
C) for each 24-bit group. Each port can be independently
programmed for either input or output. Port C can also be
configured as two 4-bit ports. These cards fully implement
Mode 0 of the 8255 PPI chip. (Consult the factory if you
desire to operate in Mode 1.) Type LS245 bi-directional
transceivers sink 24 mA (optionally 64 mA) and source 15
mA. These transceiver buffers provide hysteresis correction
on inputs and added drive capability on outputs. The direction
of the transceivers is set by software.
Input/Output
connections to IOD-24 are via a 50-pin connector on the
mounting bracket. I/O connections to IOD-72 and IOD-120
are via 50-wire interface cables that extend through rectangular
cut-outs in the mounting bracket and plug into headers on
the card. Strain relief is provided for these cables. Ready-made
displacement type ribbon cables are available from Chassis Plans as p/n CAB50F-xx. (See the Accessories section of this catalog.)
Alternate wires are connected to ground to provide shielding
and minimize crosstalk.
On
models IOD-72 and IOD-120, you can enable/disable the I/O
buffers under program control. If this is needed in a 24-bit
application, a de-populated version of IOD-72 is available
at reduced cost. Also, if only 96-bit operation is needed,
there is a jumper on the IOD-120 to set that mode of operation.
At each 24-bit port, two of the I/O lines can be used for
User Interrupts; one line to enable/disable this function
and one for the external interrupt signal. Interrupt levels
2-7 are selected by jumper on IOD-24. Interrupt levels 2-7,
10-12, 14, and 15 can be jumper selected on IOD-72 and IOD-120.
Card
I/O bus address selection is by DIP switches on the cards.
The address can be anywhere in I/O space. On power-up or
reset, all ports are automatically configured as inputs.
This prevents spurious outputs. Before use, of course, the
PPI should be software configured by writing to its control
register. The table on the previous page defines bit assignments
at each PPI.
SPECIFICATIONS
Digital
Inputs
- Logic
High: 2.0 to 5.0 VDC
- Logic
Low: -0.5 to 0.8 VDC
- Input
Load (Hi): +20 uA
- Input
Load (Lo): -200 uA
Digital
Outputs
- Logic
High: 2.5 VDC min.,source 15 mA
- Logic
Low: 0.5 VDC max., sink 24 mA
64 mA optional.
DC
Power Output
- +5
VDC from computer bus. 1A fuse included on IOD-24,
external fuse recommended if this output is used from
IOD-72 and IOD-120.
Environmental
- Power
Required: +5 VDC at 450 mA typical
- Size:
13.1 inches Long
- Operating
Temperature Range: 0° to 60 °C
- Storage
Temperature Range: -50° to 120 °C
- Humidity:
0 to 90% RH, non-condensing
