Acces PCI-DIO-24H PCI Bus Digital Input/Output Card

The Acces PCI-DIO-24H is a 24-bit digital input/output card for PCI-bus systems requiring flexible data acquisition and control. Built around 8255-5 PPI chip emulation, it delivers three independent 8-bit ports (A, B, C) with Port C subdivide-able into two 4-bit nibbles - each independently software-configurable for input or output. All 24 I/O lines employ 74ABT245B tristate buffer transceivers, sourcing 32 mA and sinking 64 mA per line.

The card supports both universal PCI and PCI-X slots at 3.3 V or 5 V logic levels via jumper selection. Configurable pull-up/pull-down resistors (10 kΩ) on all ports and a resettable 0.5 A fused +5 VDC auxiliary output enable direct integration with external control hardware. Optional 1 MHz or 10 MHz counters - based on 82C54 programmable interval timers with 48-bit range - are available for timing-critical applications.

Technical Specifications

• Digital I/O Lines: 24 bits


• Interface: PCI Bus (universal PCI, PCI-X compatible)


• Core Logic: 8255-5 PPI chip emulation; 82C55 Mode 0 programming support


• Port Configuration: Three independent 8-bit ports; Port C subdivides into two 4-bit nibbles


• Output Drive: 32 mA sourcing, 64 mA sinking per line


• Logic Levels (5 V VCCIO): Low input ≤1.5 V, high input ≥3.5 V; low output ≤0.55 V @ 64 mA, high output ≥2.4 V @ −15 mA or ≥3.8 V @ 32 mA


• Logic Levels (3.3 V VCCIO): Low input ≤0.8 V, high input ≥2.0 V; low output ≤0.55 V @ 24 mA, high output ≥2.4 V @ 24 mA


• Pull-up/Pull-down Resistors: 10 kΩ, jumper selectable per port


• Auxiliary Power Output: +5 VDC @ 0.5 A (resettable fuse)


• Power Consumption: 170 mA basic unit; 190 mA with one 1 MHz counter; 230 mA with three 1 MHz counters


• Optional Counters: 1 MHz or 10 MHz (82C54-based, 48-bit range)

Key Features

• Per-port input/output software selection


• Programmable buffer enable/disable control


• On-board 1 MHz crystal-controlled oscillator for counter operation


• High input impedance (74LS373 input buffers)


• Configurable I/O voltage (3.3 V or 5 V)

Typical Applications

• Industrial data acquisition and control


• PLC-compatible relay and discrete I/O interfacing


• Multi-channel digital switching and signal routing


• Timing-critical automation (with optional counters)

Compatibility & Integration The PCI-DIO-24H works with industry-standard I/O racks from Western Reserve Controls, Gordos, and OPTO22, supporting direct field-device integration without additional interface modules.