The Measurement Computing PCM-D24CTR3 is an ISA bus data acquisition and control board engineered for industrial and laboratory signal interfacing and device control. It delivers 24 digital I/O channels plus three 16-bit counters through a single 37-pin connector, supporting embedded systems, data logging, process automation, and machine control applications.
Technical Specifications
Digital I/O
• 24 CMOS/TTL-compatible digital I/O pins via 82C55 parallel-interface chip
• Programmable configuration: two 8-bit ports and two 4-bit ports
• Each port independently selectable for input or output operation
• Default state: all bits high-impedance on power-up and reset
• Optional pull-down resistor networks via SIP resistor locations
• Data range: 0–255 for 8-bit ports; 0–15 for 4-bit ports
• Bit-level access: 0–23 addressing on Port A
Counter I/O
• Three 16-bit down counters from 82C54 counter chip
• Load values: 0–65,535 per counter
• Counter 0 accepts internal 10 MHz crystal oscillator or external clock input
• External chaining capability for 32-bit counter formation
• Modes: HIGHONLASTCOUNT, ONESHOT, RATEGENERATOR, SQUAREWAVE, SOFTWARESTROBE, HARDWARESTROBE
Interface
• ISA bus connection with eight I/O address allocation
• 37-pin D-subminiature connector for all signal routing
– Key Features
• Programmable input/output configuration per port
• 16-bit counter precision with external clock selection
• Pull-up and pull-down resistor installation locations
• Counter cascade support for extended counting range
– Typical Applications
• Industrial process control and monitoring
• Laboratory data acquisition systems
• Machine automation and sequencing
• Real-time event logging and pulse measurement
– Compatibility & Integration
Full support for Measurement Computing’s Universal Library (UL) and Universal Library for .NET with dedicated digital I/O and counter functions. Compatible within the D24/CTR3 series ecosystem including PCI-DIO24H/CTR3, CIO-DIO24/CTR3, and PC-CARD-D24/CTR3 variants.
