5-27
5 Understanding Programming
CJ2 CPU Unit Software User’s Manual
5-2 Tasks
5
5-2-3 Interrupt Tasks
z MSKS(690)
To enable I/O interrupt tasks, execute an MSKS(690) (SET INTERRUPT MASK) instruction in the
program of a cyclic task, and enable the interrupt for the specified interrupt number of the specified
Interrupt Unit.
Operand S (the Second Operand) of MSKS(690):
The bits of FFF7 hex correspond to the interrupt inputs of the Interrupt Input Unit. Interrupt input
numbers 0 to 15 correspond to bits 0 to 15.
Example:
Precautions for Correct UsePrecautions for Correct Use
Do not enable unneeded I/O interrupt tasks. If the interrupt input is triggered by noise and there
is not a corresponding interrupt task, a fatal error (task error) will cause the program to stop.
z Interrupt Overhead Time for I/O Interrupt Tasks
The time from when the input bit of the Interrupt Input Unit (CJ1W-INT01) turns ON (or OFF) until
the CPU Unit receives the interrupt signal depends on the hardware response time. The time from
when the interrupt signal is received until the I/O interrupt task is actually executed is called the
interrupt task startup time in I/O interrupt tasks. The time it takes to return to the processing before
interruption after the interrupt task program has been executed is called the cyclic task return time.
The combination of the interrupt task startup time and the cyclic task return time is called the inter-
rupt overhead time.
Using an Interrupt Input Unit
*1 Using High-speed interrupt function
Refer to 10-2-6 High-speed Interrupt Function for information on High-speed interrupt function.
Note I/O interrupt tasks can be executed during user program execution, I/O refreshing, peripheral servicing, or
overhead processing. (An I/O interrupt task can also be executed even if an instruction is being executed.
The instruction will be interrupted.) An input interrupt will not be processed immediately if it occurs during
execution of an interrupt task. The current interrupt task will be executed to the end first, and then execution
of the new interrupt will be started after the cyclic task return time and interrupt task startup time have
expired.
Item
Time
CJ2H CPU Units CJ2M CPU Units
Hardware response (CJ1W-INT01) Upward differentiation: 0.05 ms, Downward differentiation: 0.5
ms
Interrupt over-
head time
Interrupt task startup time
26 µs or 17 µs
*1
(30 µs for unit version 1.0)
31 µs
Cyclic task return time
11 µs or 8 µs
*1
(15 µs for unit version 1.0)
10 µs
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1
F hex F hex F hex 7 hex
Example when the interrupt condition
is the third bit.
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