Keithley Instruments PIO-24 Digital Interface Board

The Keithley Instruments PIO-24 Digital Interface Board is an ISA bus parallel digital I/O card that delivers 24 high-current programmable I/O lines for PC-based data acquisition, industrial automation, and automated test systems. It uses an Intel 8255 Programmable Peripheral Interface (Mode 0 Emulation) with three 8‑bit ports (Port A, Port B, Port C) and TTL/CMOS compatible logic, with input high thresholds of 2.0–5.0 V and input low thresholds of -0.5 to 0.8 V, plus a programmable interrupt input with selectable PC IRQ levels. Each output can sink up to 64 mA, power is supplied from the +5 V ISA bus (approximately 400 mA), and the board uses a 37-pin D-Sub male I/O connector. Operating temperature is 0°C to 70°C, with typical applications including relay control, peripheral communication, digital monitoring, machine automation, data acquisition, and automated test equipment (ATE). Common replacements include Keithley Instruments KPCI-PIO24 and PIO-12.