IOD-144
Digital Input/Output Card
FEATURES
- 144
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
This
is a 144-bit full-size card. 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.
I/O
connections 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. Alternate wires are connected to ground
to provide shielding and minimize crosstalk.
The
I/O buffers can be enabled/disabled under program control.
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, 10-12, 14, and 15 can be jumper selected on the IOD-144.
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 milliamperes optional
Power
Output
Environmental
- Power
Required: +5 VDC at 450 mA typical
- Size:
13.1 inches Long
- Operating
Temperature Range: 0o to 60 oC
- Storage
Temperature Range: -50o to 120 oC
- Humidity:
0 to 90% RH, non-condensing
