Toshiba T2N - Manual (Page 130)

3.User Program Running Control
User’s manual 117
(1) Priority control of interrupt program
When several interrupt conditions occur simultaneously, the programs are run
in the order of priority shown in the following table (the lower the numerical
value the higher the level of prriority). Also, if other interrupt conditions occur
during an interrupt program run, the interrput conditions are put on hold
during running of the interrput program, and after it is completed, they are
run in order of priority.
Interrupt program Level of priority Level of priority within
classification
Timer interrupt 0 -
I/O interrupt No.1 0
I/O interrupt No.2 1
I/O interrupt No.3 2
I/O interrupt No.4
1
3
The timer interrupt has the highest level of priority, followed by the I/O
interrupt programs in order.
With respect to the level of priority for I/O interrupt, the I/O interrupt form
the I/O module with interrupt function nearest the CPU has the highest level
of priority. Refer to (3) below regarding the correspondence between
interrupt programs and I/O modules.
(2) Interrupt enable/disable
You can switch between interrupt enable and disable by executing DI
instruction (interrupt disable) or EI instruction (interrupt enable) in the user
program. The interrupt request is hold during interrupt is prohibited after
executing the DI instruction. After the EI instruction is executed and this
request is permitted.
Also, interrupt is prohibited in the first scan after the transition to RUN
mode and it is permitted from the second scan.
(3) Allocation of I/O interrupt program
The I/O interrupt with the lowest number corresponds to the I/O module
with interrupt function nearest the CPU.
I/O modules with interrupt function is under development.
NOTE