Task 1: Enable / Disable The Interrupts; Task 2: Place Numbered Interrupt Subroutines After The End Statement - DirectLOGIC DL405 Manual

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Task 1:
Enable / Disable
the Interrupts
Task 2:
Place Numbered
Interrupt
Subroutines after
the END Statement
The CPU does not automatically monitor the
interrupt input signals. Instead, you have to use
an Enable Interrupts (ENI) instruction in your
ladder program to do this. Why does it work this
way? Simple. There may be times when you
don't want the CPU to acknowledge the
interrupt signals. For example, you may only
want to monitor the interrupts if a certain safety
parameter is true (or false). If you don't include
this instruction, the interrupts will be ignored .
The ENI instruction is used just like an output coil,
that is, you use an input contact, comparative
boolean contact, etc. that enables the interrupts.
Since you can enable the interrupts, it also makes sense that you be able to disable
the interrupts. (Actually, if you do not tell the CPU under what conditions it is to
disable the interrupts once they have been enabled, it will assume they will always
be enabled.) You can disable the interrupts with the Disable Interrupts (DISI)
instruction. This instruction also appears as an output coil and can be triggered like
any other type of output coil.
Helpful Hints: In our Direct SOFT programming software, the ENI and DISI
instructions are found on the Coil Browser. Look under the class listed as "Interrupt."
Each interrupt input
corresponding interrupt subroutine. These
interrupt subroutines are placed after the END
statement, which is the last instruction in the
ladder program.
The interrupt subroutine for X0 should be
labeled INTO0, the routine for X1 should be
labeled INTO1, etc. If you're using two interrupt
modules (D4–440 only), then the second
module would use INT10 for X20, INT11 for
X21, etc. The CPU automatically executes the
interrupt subroutine that corresponds to the
interrupt input point.
NOTE: That's the letter "O" in front of the number. The Direct SOFT screen
automatically puts an "O" there for you and it must be there. Don't delete it!
WARNING: If you have a D4–440 CPU, two hardware interrupt modules, and
you are using a Timed Interrupt, then you cannot use INTO17 as a hardware
triggered interrupt subroutine. (This means you could not use the 8th
interrupt input point on the second Interrupt module.) The software interrupt
is triggered off of Interrupt 17, and you don't want a conflict.
Helpful Hints: In our Direct SOFT programming software, the INT instructions are
found on the Box Browser. Look under the class listed as "Interrupt."
point needs a
INT
If X40 is on, Interrupts
are enabled
X40
ENI
X42
DISI
If X42 is off, Interrupts
are disabled
END
X0 Interrupt
O 0
Subroutine
X20
Y5
OUTI