Chapter 9 PLC Operation
9-8
9.1.4
Relationship of Each Scan Type
When three types of scan occur at the same time, scan is executed in the order of periodical scan, then interrupt scan, and
then normal scan.
Figure 9.15 Relational diagram of scan operation
Table 9.3 List of interrupt label
Interrupt label
Cause of startup
Interrupt label
Cause of startup
INT0
Interrupt every 10 ms
INT20
Counter 1 on-preset match
INT1
Interrupt every 20 ms
INT21
Counter 1 off-preset match
INT2
Interrupt every 40 ms
INT22
Counter 2 on-preset match
INT16
Interrupt of interrupt input 1
INT23
Counter 2 off-preset match
INT17
Interrupt of interrupt input 2
INT24
Counter 3 on-preset match
INT18
Interrupt of interrupt input 3
INT25
Counter 3 off-preset match
INT19
Interrupt of interrupt input 4
INT26
Counter 4 on-preset match
INT27
Counter 4 off-preset match
Low
High
Execution priority
Interrupt scan Periodical scan
Normal scan
Normal
scan
Ladder program
END scan
Processing
Normal scan
Interrupt scan
10 ms
10 ms
10 ms
10 ms
Periodical scan
Periodical system processing
INT16
INT17
INT18
:
:
INT27
10 ms periodical
program
20 ms periodical
program
40 ms periodical
program
Interrupt analysis
processing
Interrupt program
Interrupt
scan
Periodical
scan
Summary of Contents for HIDIC MICRO-EH
Page 1: ...HITACHI PROGRAMMABLE CONTROLLER APPLICATION MANUAL NJI 350B X ...
Page 12: ...MEMO ...
Page 14: ...Chapter 1 Features 1 2 MEMO ...
Page 50: ...Chapter 4 Product lineup and wiring 4 18 MEMO ...
Page 196: ...Chapter 5 Instruction Specifications 5 146 ...
Page 263: ...Chapter 11 Communication Specifications 11 10 MEMO ...