Advantech PCL-720 Digital I/O and Counter Card

The Advantech PCL-720 is an ISA bus digital I/O and counter card for PC-compatible systems, delivering 32 independent digital input channels and 32 digital output channels alongside three programmable 16-bit counter/timer channels. Built around the Intel 8253/8254 programmable interval timer, the card supports six software-selectable operational modes including rate generation, event counting, real-time clock, one-shot timing, delay generation, and square wave generation. TTL/DTL compatible I/O operates through 74LS244 driver/buffer circuits, providing high output drive capacity and minimal input loading.

Programmable counter frequencies reach 2.6 MHz with count values from 0 to 65,535.

Technical Specifications

Digital I/O Architecture

• 32 input channels, 32 output channels (TTL/DTL compatible)


• 74LS244 driver/buffer circuits for signal conditioning


• Five 20-pin insulation displacement connectors (two rear-panel accessible, three onboard)


• Selectable I/O base address: 200h to 3F8h (four consecutive ports) Counter/Timer Performance


• Three independent 16-bit counters (Intel 8253/8254)


• Programmable count rate to 2.6 MHz


• Count range: 0 to 65,535


• Six operational modes: rate generator, event counter, real-time clock, digital one-shot, time delay generator, square wave generator


• Onboard clock sources: 1 MHz, 100 kHz, 10 kHz (jumper-selectable, with frequency doubling/halving/quartering capability) Physical & Environmental


• Dimensions: 205 mm × 100 mm (8" × 3.9")


• Breadboard area: 651 plated-through holes (31 × 21 @ 0.10" pitch)


• Power: +5 V @ 500 mA typical


• Operating temperature: 0 to +60 °C


• Storage temperature: -20 to +70 °C


• Humidity: 5 to 95% RH non-condensing (IEC 68-2-3)

Key Features

• Onboard breadboard for custom circuit integration


• Jumper-configurable clock source selection


• PCL-720+ variant compatibility (interchangeable)

Typical Applications Industrial automation, process control, real-time event logging, pulse measurement, frequency generation, and timing applications requiring flexible counter modes.

Compatibility & Integration Supports daughter boards including PCLD-782 (16-ch opto-isolated input), PCLD-785 (16-ch relay output), and PCLD-786 (8-ch SSR).