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2.3.2
Timed Interrupts
A block can be configured to execute on a specified time interval with an initial delay (if specified)
applied on a STOP Mode to RUN Mode transition of the CPU.
To configure a timed interrupt block, specify the following parameters in the scheduling properties
for the block:
Time Base
The smallest unit of time that you can specify for Interval and Delay. The time base can be 1.0
second, 0.10 second, or 0.01 second, or 0.001 second.
Interval
Specifies how frequently the block executes in multiples of the time base.
Delay
(Optional) Specifies an additional delay for the first execution of the block in multiples of the
time base.
The first execution of a Timed Interrupt block will occur at
((delay * time base) + (interval * time base)) after the CPU is placed in RUN Mode.
2.3.3
I/O Interrupts
A block can be triggered by an interrupt input from certain hardware modules. For example, on the
32-Circuit 24 Vdc Input Module (IC697MDL650), the first input can be configured to generate an
interrupt on either the rising or falling edge of the input signal. If the interrupt is enabled in the
module configuration, that input can serve as a trigger to cause the execution of a block.
To configure an I/O interrupt, specify a trigger in the scheduling properties for the block. The trigger
must be a global variable in %I, %AI or %AQ memory, or an I/O variable. (An I/O variable is a form of
symbolic variable that is mapped to a module I/O point in hardware configuration.)
PACSystems modules that can trigger user interrupt logic always send the interrupt to the CPU
when configured to do so. If the CPU is in STOP mode when it receives the interrupt, it does not run
the user interrupt block. The CPU does not run the user interrupt block when it transitions from
STOP Mode to RUN Mode.
2.3.4
Module Interrupts
A block can be triggered by an interrupt from a module that supports I/O interrupts if the Interrupt
parameter is enabled in the module's hardware configuration.
To configure a module interrupt, specify the module by rack/slot/interrupt ID as the Trigger in the
scheduling properties for the block.
GFK-2950C
February 2018
Chapter 2. Program Organization
27
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