The NI PC-DIO-24 is a 24-bit parallel digital I/O ISA card for industrial automation, data acquisition, and control applications. Built around the OKI 82C55A programmable peripheral interface, it delivers 24 independent digital I/O lines compatible with 5 V TTL/CMOS signaling. The card supports unidirectional and bidirectional bus modes with interrupt generation capability, operating at transfer rates up to 50 Kbytes/s under NI-DAQ software control. Plug and Play configuration eliminates external card manager requirements, while user-defined power-up states and 2-wire handshake support enable flexible system integration. The board accepts 8-bit, 16-bit, or 24-bit digital I/O operations across its static I/O ports.
Technical Specifications
• Digital I/O Channels: 24 lines
• Interface: ISA bus with 50-pin male ribbon-cable connector
• I/O Signal Compatibility: 5 V TTL/CMOS
• Programmable Peripheral Interface: OKI 82C55A or equivalent
• Operating Modes: Unidirectional, bidirectional
• I/O Voltage Rating: -0.5 V to +5.5 V with respect to GND
• Output Signal: 4.65 V to 5.25 VDC, maximum 1 A (Pin 49)
• Power Consumption: Typical 0.45 A at +5 VDC (±10%); maximum 1 A
• Data Transfer Rate: Up to 50 Kbytes/s with NI-DAQ software; typical 1–10 Kbytes/s
• Operating Temperature: 0°C to 70°C
• Relative Humidity: 5% to 90% non-condensing
– Key Features
• Interrupt request generation for event-driven applications
• 2-wire handshake capability for protocol-based I/O control
• Plug and Play configuration without external managers
• User-defined power-up state initialization
• Register-level programming details provided in user manual appendices
– Typical Applications
• Industrial automation and control systems
• Data acquisition platforms
• Peripheral equipment interfacing
• Multi-port digital signal management
– Compatibility & Integration
The PC-DIO-24 integrates with NI-DAQ software and supports cross-platform development. Example programs provided in manuals use C. ISA bus compatibility allows deployment across legacy and contemporary PC platforms.
