Delta AH500 Programming Manual page 315

set to ON.
(b) If the external 24 V voltage of the first local extension backplane is abnormal, bit 1 in SR731
will be set to ON.
4. The external interrupts (I40~I251)
If a peripheral device, e.g. a special I/O module, sends an interrupt request, the PLC will
execute the specific interrupt task.
5. The timed interrupts (I252~I255)
Timed interrupt 0 (I252): The default value is 100 milliseconds (1~1000 milliseconds).
Timed interrupt 1 (I253): The default value is 40 milliseconds (1~1000 milliseconds).
Timed interrupt 2 (I254): The default value is 20 milliseconds (1~1000 milliseconds).
Timed interrupt 3 (I255): The default value is 10 milliseconds (1~1000 milliseconds).
The timed interrupt task is executed every specific period of time. For example, the timed
interrupt task is executed every 10 milliseconds.

The priority order is a follows.
Interrupt number
I0
I1
I2
I3
I4
I5
I6
I7
I8
I9
I10
I11
I12
I13
I14
I15
I16
I17
I18
I19
I20
I21
I22
I23
I24
I25
I26
I27
I28
I29
I30
I31
I32
Description
I/O interrupt 0
I/O interrupt 1
I/O interrupt 2
I/O interrupt 3
I/O interrupt 4
I/O interrupt 5
I/O interrupt 6
I/O interrupt 7
I/O interrupt 8
I/O interrupt 9
I/O interrupt 10
I/O interrupt 11
I/O interrupt 12
I/O interrupt 13
I/O interrupt 14
I/O interrupt 15
I/O interrupt 16
I/O interrupt 17
I/O interrupt 18
I/O interrupt 19
I/O interrupt 20
I/O interrupt 21
I/O interrupt 22
I/O interrupt 23
I/O interrupt 24
I/O interrupt 25
I/O interrupt 26
I/O interrupt 27
I/O interrupt 28
I/O interrupt 29
I/O interrupt 30
I/O interrupt 31
Communication interrupt
(COM1)
Ch a pt er 6 Ap p l i ed I ns t r uc t i ons
Priority order
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
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