30
Interrupt Functions
Section 1-4
When the program is executed, operation will be as shown in the following
diagram.
Note
1.
The counter will continue operating even while the interrupt routine is being
executed.
2.
The input interrupt will remain masked.
1-4-4
Masking All Interrupts
The INT(89) instruction can be used to mask and unmask all interrupts as a
group, including input interrupts, interval timer interrupts, and high-speed
counter interrupts. The mask is in addition to any masks on the individual
types of interrupts. Furthermore, clearing the masks for all interrupts does not
clear the masks on the individual types of interrupts, but restores them to the
masked conditions that existed before INT(89) was executed to mask them as
a group.
Do not use INT(89) to mask interrupts unless it is necessary to temporarily
mask all interrupts and always use INT(89) instructions in pairs to do so, using
the first INT(89) instruction to mask and the second one to unmask interrupts.
INT(89) cannot be used to mask and unmask all interrupts from within inter-
rupt routines.
Masking Interrupts
Use the INT(89) instruction to disable all interrupts.
If an interrupt is generated while interrupts are masked, interrupt processing
will not be executed but the interrupt will be recorded for the input, interval
timer, and high-speed counter interrupts. The interrupts will then be serviced
as soon as interrupts are unmasked.
00000
00001
00100
Subroutine 000
Subroutine 001
(see note 1)
(see note 1)
(see note 2)
10 counts
10 counts
20 counts
Interrupts masked/unmasked by INT(89)
Source Unit or Board
Input interrupts
CPU Unit
Interval timer interrupts
High-speed counter 0 interrupt
High-speed counter 1 and 2 interrupts
Pulse I/O Board
High-speed counter 1 and 2 interrupts
Absolute Encoder Interface Board
(@)INT(89)
100
000
000
