The Measurement Computing PCI-DIO48H is a high-density digital I/O module for PCI-compatible systems, delivering 48 bits of individually programmable bidirectional logic-level I/O. The board emulates the 82C55 controller in Mode 0, organizing channels into two 24-bit groups. Each group contains Port A (8 bits), Port B (8 bits), and Port C (split into 4-bit nibbles C-HI and C-LO). All I/O lines are independently configurable as input or output, defaulting to high-impedance input at power-up or reset.
Technical Specifications
• Digital I/O Channels: 48 bits, bidirectional
• Organization: Two 24-bit groups; 82C55 Mode 0 emulation
• Port Structure: Port A (8 bits), Port B (8 bits), Port C (2 × 4-bit nibbles)
• Input Compatibility: TTL-level, high impedance (74LS373 buffers)
– Input High: 2.0 V minimum to 5.5 V absolute maximum
– Input Low: 0.8 V maximum to −0.5 V absolute minimum
• Output Drive: Buffered TTL (74ABT244 or 74S244 drivers)
– Output High: 2.0 V minimum at −15 mA source
– Output Low: 0.55 V maximum at 64 mA sink
– Current Sink Capability: 64 mA
– Current Source Capability: 15 mA
• Connector: 50-pin header for digital I/O lines
• Protection: One 1 A slow-blow fuse on +5 V user output; one spare fuse included
• Default State: All I/O bits default to input (high impedance) on power-up or reset
– Key Features
• Plug-and-play operation with no jumpers or configuration switches
• Individual port programmability for maximum flexibility
• Optional pull-up or pull-down resistor locations provided on board
• Daisy-chain capable for expansion with compatible accessories (CIO-ERB24, SSR-RACK24)
• PCI bus enumeration via system BIOS and Plug-and-Play software
– Typical Applications
• Industrial control and relay logic switching
• Machine automation and process monitoring
• Test system instrumentation and data acquisition
• Hardware-in-the-loop testing environments
– Compatibility & Integration
The PCI-DIO48H integrates directly into any PCI-compatible computer without manual address configuration. Daisy-chain expansion with relay output boards and I/O module racks allows full utilization of all 48 digital lines in multi-module configurations.
