Owner's manual

Chapter 4: PowerDAQ Software
58
High-Speed interrupts
A high-Speed interrupt line is powerful feature of the PowerDAQ DIO
boards.
IRQ lines act as a part of the Digital input subsystem and use the same
mechanism as digital input change-of-state interrupts uses. IRQ reacts
to the external event in 100nS and interrupt the host PC in less, than
1uS but host PC reaction depends on the current system load and
operational system used.
IRQx terminal detects only negative edge of the incoming signal. The
minimum length of the negative pulse must be at least 20nS to be
properly detected by the board.
Please note, that IRQC terminal is used also as an external trigger input
and IRQD terminal used as a service input (connected to TMR1 output),
when events from the TMR2 counter streamed on the-CT board.
PD-DIO-CBL-16 or equivalent cable must be used to connect PDx-DIO
J3 connector to the PDx-DIO-STP-64 when high-speed IRQs are used.
See dsp_irqs.c example for the details.