The Measurement Computing USB-DIO24/37 is a 24-channel digital I/O device that provides plug-and-play connectivity for data acquisition and control applications without requiring external power. The device emulates an 82C55 programmable peripheral interface in mode 0, offering independent port configuration with 5 V logic levels. USB bus power eliminates external supply requirements, making it ideal for portable and bench-top measurement setups.
Technical Specifications
Digital I/O Channels
• 24 digital I/O lines configured as two 8-bit and two 4-bit ports
• Each port independently configurable for input or output; default is input
• 82C55 emulation in mode 0
• All pins pulled high to +5 V via 47 kΩ resistors on power-up and reset
Input Specifications
• Input high voltage: 2.0 V minimum to 5.5 V absolute maximum
• Input low voltage: −0.5 V absolute minimum to 0.8 V maximum
Output Specifications
• Sink current: Up to 64 mA per line (maximum 6 lines simultaneously); 18 mA per line for all 24 outputs
• Source current: 15 mA per output
• Output high voltage: 3.0 V minimum (at −2.5 mA)
• Output low voltage: 0.4 V maximum (at −2.5 mA)
• Maximum I/O voltage: 5.5 V
Counter
• One 32-bit external event counter
• TTL input, rising edge triggered
• Frequency input capability: Up to 1 MHz
Power
• USB bus power: +5 V only; no external supply required
• Supply current: 20 mA typical, 40 mA maximum (includes 5 mA for status LED)
• Self-powered hub: 4.5 V to 5.25 V; maximum 460 mA available
• Bus-powered hub: 4.1 V to 5.25 V
– Key Features
• USB 1.1 and USB 2.0 compatible
• 37-pin D-type connector with 24 I/O lines, one counter input, six grounds, two power connections
• Compatible with C37FF-x unshielded ribbon cable and C37FFS-x shielded round cable
• Windows and Linux operating system support
– Typical Applications
• Digital signal monitoring and control
• TTL event counting up to 1 MHz
• Industrial automation and test equipment integration
• Laboratory measurement systems
– Compatibility & Integration
Connects directly to USB 1.1 and USB 2.0 ports. Compatible with self-powered and bus-powered hubs. Operates across Windows and Linux platforms.
