Keithley PDISO-8 8-Channel Isolated Digital I/O Board

The Keithley PDISO-8 is an 8-channel isolated digital I/O board for control and sensing applications requiring galvanic isolation and ground-loop prevention. It combines 8 electromechanical relay outputs with 8 optically isolated inputs, interfacing through an ISA-bus compatible architecture and 37-pin D-type connector. Designed for industrial automation, process control, and laboratory environments demanding reliable signal integrity. ## Technical Specifications Relay Outputs • 8 channels: 5 Form C (SPDT) contacts, 3 Form A (SPST) contacts • Contact rating: 3 A @ 125 Vrms (resistive load) • Contact resistance: 100 mΩ max (initial) • Operating time: 20 ms max; Release time: 10 ms max • Mechanical life: 10⁷ operations minimum • Electrical life: 10⁵ operations minimum @ full load • Power-on state: De-energized (relays resting on NC contact) Digital Inputs • 8 channels, non-polarized optically isolated • Input range: 5–24 VDC or VAC (50–1,000 Hz) • Input resistance: 470 Ω to 1.6 kΩ • Response time: 5 V minimum; Input low level: <2.5 V maximum • Mixed AC/DC input capability Power & Environmental • +5 V supply: 0.4 A (all relays off), 1.0 A (all relays on) • Operating temperature: 0 to +50 °C • Storage temperature: –20 to +70 °C • Humidity: 0 to 90% non-condensing • Dimensions: 6.0 in × 4.25 in × 1.1 in (152 mm × 108 mm × 28 mm) • Weight: 213 g ## Key Features • Functional isolation prevents ground-loop faults and cross-talk • Dry relay contacts rated for both AC and DC switching • Channel-by-channel software filter control for noise rejection • Accepts mixed voltage supplies (AC and DC simultaneously) • Standard ISA-bus interface; backward compatible with legacy systems • Optional screw-terminal connector available (STC-37) ## Typical Applications Industrial automation, distributed process control, data acquisition systems with isolated switching, laboratory test benches, equipment monitoring and protection circuits. ## Compatibility & Integration ISA-bus compatible PC interface; 32-bit DriverLINX drivers. Bundled with ExceLINX, VisualSCOPE, and LabVIEW support. Requires Windows 95/98/NT environment (Pentium-series processor recommended).