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96 T1-16S User’s Manual
6. Programming Information

6.6.4 I/O interrupt programs

The I/O interrupt program is also the highest priority task. It is executed immediately
when the interrupt factor is generated, with suspending other operation.
The following 4 types I/O interrupt programs are supported in the T1/T1S.
(1) I/O interrupt #1
The I/O interrupt #1 is used with the high speed counter function. When the count
value reaches the preset value, etc., the I/O interrupt #1 is activated immediately
with suspending other operation. The end of the I/O interrupt #1 is recognized by
the IRET instruction. For detailed information, refer to section 8.3.
(2) I/O interrupt #2
The I/O interrupt #2 is also used with the high speed counter function. Refer to
section 8.3 for details.
(3) I/O interrupt #3
The I/O interrupt #3 is used with the interrupt input function. When the state of the
interrupt input is changed from OFF to ON (or ON to OFF), the I/O interrupt #3 is
activated immediately with suspending other operation. The end of the I/O
interrupt #3 is also recognized by the IRET instruction. For detailed information,
refer to section 8.4.
(4) I/O interrupt #4
The I/O interrupt #4 is also used with the interrupt input function. Refer to section
8.4 for details.
If an interrupt factor is generated while other interrupt program is executing (including
the timer interrupt), the interrupt factor is held. Then it will be activated after finishing
the other interrupt program execution.
If two or more interrupt factors are generated at the same time, the priority is as
follows.
Timer > I/O #1 > I/O #2 > I/O #3 > I/O #4