Chapter 2. Program Organization
GFK-2950C February 2018 25
2.3 Interrupt-Driven Blocks
Three types of interrupts can be used to start a block’s execution:
▪ Timed Interrupts are generated by the CPU based on a user-specified time interval with an
initial delay (if specified) applied on STOP Mode to RUN Mode transition of the CPU.
▪ I/O Interrupts are generated by I/O modules to indicate discrete input state changes
(rising/falling edge), analog range limits (low/high alarms), and high-speed signal counting
events.
▪ Module Interrupts are generated by VME modules. A single interrupt is supported per module.
Caution
Interrupt-driven block execution can interrupt the
execution of non-interrupt-driven logic. Unexpected
results may occur if the interrupting logic and
interrupted logic access the same data. If necessary,
Service Request #17 or Service Request # 32 can be
used to temporarily mask I/O and Timed Interrupt-
driven logic from executing when shared data is being
accessed.
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