The Keithley PIO-SSR-120 is a multi-channel parallel digital I/O board that connects computers with ISA bus slots to external devices for data acquisition and control applications. It provides 120 TTL/NMOS/CMOS-compatible digital I/O lines organized across five 50-pin headers, with each header supporting 24 channels. The board can directly drive solid-state relays and, when paired with external SSRs, enables control and sensing of voltages up to 280VAC and 280VDC while delivering 4000Vrms isolation.
## Technical Specifications
• **Digital I/O Lines:** 120 channels
• **Signal Compatibility:** TTL/NMOS/CMOS
• **Sink Current:** 24 mA per line
• **Source Current:** -15 mA per line
• **Output Connections:** Five 50-pin headers (24 channels per header)
• **Isolation (with external SSRs):** 4000Vrms
• **Maximum Voltage (with external SSRs):** 280VAC, 280VDC
• **Power Consumption:** +5VDC @ 1.6A typical
• **Operating Temperature:** 0 to 50°C
• **Storage Temperature:** 0 to 70°C
• **Humidity:** 0 to 90% non-condensing
• **Physical Form Factor:** ISA half-slot (5in × 4.25in × 0.75in)
• **Weight:** 4oz
## Key Features
• Interrupt-capable architecture for event-driven applications
• Direct SSR drive capability for high-power switching without intermediate relay logic
• Isolation rated to 4000Vrms when used with external solid-state relays
• Parallel I/O configuration for high-throughput digital signal management
• Low power draw from host ISA bus
## Typical Applications
• Industrial automation control and monitoring
• Laboratory research requiring multi-channel digital I/O
• Automated test equipment and ATE systems
• High-voltage load switching and sensing
• Data acquisition systems requiring isolated digital channels
## Compatibility & Integration
• **Bus Interface:** ISA
• **Operating Systems:** MS-DOS, Windows 95/98
• **Bundled Software:** ExceLINX, VisualSCOPE, TestPoint, LabVIEW drivers
• **Power Rails:** +5V, ±12V, -5V available from ISA connector
