48(24 for USB4751L) TTL level digital I/O lines.
Emulates mode 0 of 8255 PPI
Buffered circuits provide higher driving capability
Interrupt handling
Interrupt output pin for simultaneously triggering external devices with the interrupt
2(1 for USB4751L) IDE 50 pin connector in Opto-22 pin assignment
Output status readback
2 counter with PWM, Divider, Counting & Freqency Measure functions.
Keeps port I/O settings and digital output states after hot system reset
Supports dry contact and wet contact
Industrial AC/DC I/O devices monitoring and control
Relay and switch monitoring and control
Parallel data transfer
Sensing the signals of TTL, DTL, CMOS logic
Driving indicator LEDs
Two lines in each I/O port (C0 and C4) are connected to the interrupt circuitry. The "Interrupt Control Register" of the USB-4751 controls how the combination of the 2 signals generates an interrupt. Two interrupt request signals can be generated at the same time, and then the software can service these two request signals by ISR. The dual interrupt sources provide the card with more capability and flexibility.
The USB-4751 includes 2 channel compatible programmable counters to provide 2 24-bit multi-function counters. Each can provide Counter, PWM, Divider, Frequency measure functions, all the input functions execute on falling edge when the counter gate is high level.
Note:
1. The USB chip on your system may have a limitation on the number of USB devices it supports. Normally, only five USB-4751 devices can be supported.