Hitachi HIDIC MICRO-EH Applications Manual page 235

9.1 RUN Start
When the MICRO-EH switches to the operating state, the user program is executed in sequence from the beginning. The
user programs consist of a normal scan program and periodical scan program. In addition to these programs, there is a
subroutine area defined as a subroutine.
No. Program classification
1 Normal scan program
2 Periodical scan program
3 Interrupt scan program
4 Subroutine
Table 9.2 Program classification
Description
This is the program that is normally executed.
When the program has been executed to the
END instruction, execution starts again from
the beginning.
Congestion error is monitored according to the
congestion check time set by the user. It is
monitored from the beginning of the program
to the END instruction.
When it is specified to continue during
congestion (R7C0), the operation continues
even if a congestion error occurs.
This program is executed periodically at
intervals of 10 ms, 20 ms, or 40 ms.
INT0: Every 10 ms
INT1: Every 20 ms
INT2: Every 40 ms
Each execution cycle time becomes a
congestion error monitoring time.
When it is specified to continue during
congestion (R7C1), the periodical scan
program is suspended during operation.
When there is an input to the input terminal
assigned to the interrupt input, the interrupt
program (INT16 to INT19) corresponding to
that input starts up.
If another interrupt caused by the same factor
occurs during the execution of the interrupt
program, a congestion error occurs. When the
operation continuation at a congestion error
(R7C2) is specified, the same interrupt scan
program is run from the beginning again.
If the counter value exceeds the preset value, a
corresponding interrupt program (INT20 to
INT27) starts up according to the counter
number.
This is a program called by the CALL
instruction.
9-2
Chapter 9 PLC Operation
Expression
Normal scan
program
END
Described in the area after the END
instruction.
INTn
Periodic scan
program
RTI
n = 0, 1, 2
Described in the area after the END
instruction
INTn
Interrupt scan
program
RTI
n = 16 to 19
Described in the area after the END
instruction
INTn
Interrupt scan
program
RTI
n = 20 to 27
Described in the area after the END
instruction
SBn
Subroutine
program
RTS
n = 0 to 99