IOD-64 64-Channel Digital I/O Board

IOD-64
Digital Input/Output Card

FEATURES

64 channels of digital I/O
Eight 8-bit ports of directly addressable bi-directional I/O
Bit-by-bit programmable for input or output
I/O buffers can be enabled/disabled under program control
Compatible with industry standard I/O racks from Opto-22, Western Reserve Controls, DuTec, Gordos, Potter & Brumfield, etc
User selectable to occupy any eight consecutive I/O addresses.
Control and I/O ports separately addressable to allow I/O ports for multiple cards to occupy consecutive addresses
Four inputs may be directed to hardware interrupts

FUNCTIONAL DESCRIPTION

Model IOD-64 accepts up to 64 bits of Digital I/O and the card is organized into eight 8-bit ports. Input voltages can range up to 30 VDC. This card is particularly useful for interface between an ISA-Bus computer and industry-standard, optically-isolated, solid-state I/O module mounting racks. Up to four 16-position I/O racks can be controlled and each point is directly addressable by the host computer.

Variable I/O-mapped addressing allows you to select eight consecutive addresses plus a separate control port from any I/O addresses between 200 hex and 3FF hex. In addition, you can drive four of the host's interrupts from inputs applied to IOD-64. Read/Write Select Logic manages all data transmission between the computer and the I/O ports. There are five inputs to the select logic:

Reset: When this line goes high, either on power-up or during a low-line voltage loss, it clears the Output Control Latch disabling all output ports. This assures that there will be no spurious outputs.
Address Enable (AEN): When this line is driven low, it enables the PC I/O channel. The Read/Write Select Logic then checks the value on the address bus by comparing that address to the I/O Port and Control Addresses.
I/O Write Command (IOW): When this line is low and the address comparison is true, the IOD-64 card reads data from the data bus.
I/O Read Command (IOR): When this line is low and the address comparison is true, the IOD-64 card writes data to the data bus.
Address (ADDR): These ten lines are used to address the Control Port and I/O Ports.

When the Data Bus Buffer is enabled by the Read/Write Select Logic, it permits data transfer between the host computer and the IOD-64. The Output Control Latch disables any or all of the eight 8-bit I/O ports. Inputs to the Output Control Latch are:

Data from the host computer data bus.
When the PC-Reset line is high, it automatically clears the Output Control Latch which, in turn, disables all outputs as previously described.
When the Output Control Latch is enabled by the Read/Write Select Logic, it will disable individual ports as required by programming.

The IRQ Control, when enabled by the Read/Write Select Logic, routes external inputs received from any or all of the last four inputs of PORT 7 to IRQ4 through IRQ7 of the host computer.

PIN CONNECTIONS

Four 50-pin headers are provided; one for each group of 16 bits. Sixteen bi-directional data lines are alternated with 16 ground lines on each connector. Also, +5 VDC power is available and digital ground.

SPECIFICATIONS

Digital Inputs

Logic High: 2.0 to 30 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. to 30.0 VDC (w/ external pull-ups), source 15 mA
Logic Low: 0.5 VDC max., sink up to 40 mA

Power Output

+5 VDC from computer bus (external 1A fast-blow fuse recommended)

Environmental

Power Required: +5 VDC at 450 mA typical
Size: 13.1 inches long
Operating Temperature Range: 0^o to 60 ^oC
Storage Temperature Range: -50^o to 120 ^oC
Humidity: 0 to 90% RH, non-condensing

IOD-64 Digital Input/Output Card