Automationdirect.com DL06, User Manual

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DL06 Micro PLC User Manual, 3rd Edition, Rev. E
5-183
Chapter 5: Standard RLL Instructions
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Typically, interrupts are used in an application when a fast response to an input is needed
or a program section must execute faster than the normal CPU scan. The interrupt label
and all associated logic must be placed after the End statement in the program. When an
interrupt occurs, the CPU will complete execution of the current instruction it is processing
in ladder logic, then execute the interrupt routine. After interrupt routine execution, the
ladder program resumes from the point at which it was interrupted.
See Chapter 3, the section on Mode 40 (Interrupt) Operation for more details on interrupt
configuration. In the DL06, only one software interrupt is available. The software interrupt
uses interrupt #00 (INT 0), which means the hardware interrupt #0 and the software
interrupt cannot be used together. Hardware interrupts are labeled in octal to correspond
with the hardware input signal (e.g. X1 will initiate INT 1).
O aaa INT
IRT
IRTC
ENI
Operand Data Type DL06 Range
aaa
Constant O 1-FFFF
DS Used
HPP Used
DS Used
HPP Used
DS Used
HPP Used
DS Used
HPP Used
Interrupt Instructions
Interrupt (INT)
The Interrupt instruction allows a section of ladder logic to be placed
below the main body of the program and executed only when needed.
High-Speed I/O Modes 10, 20, and 40 can generate an interrupt.
With Mode 40, you may select an external interrupt (input X0), or a
time-based interrupt (3–999 ms).
Interrupt Return (IRT)
An Interrupt Return is normally executed as the last instruction in the
interrupt routine. It returns the CPU to the point in the main program
from which it was called. The Interrupt Return is a stand-alone instruction
(no input contact on the rung).
Interrupt Return Conditional (IRTC)
The Interrupt Return Conditional instruction is a optional instruction
used with an input contact to implement a conditional return from the
interrupt routine. The Interrupt Return is required to terminate the
interrupt routine.
Enable Interrupts (ENI)
The Enable Interrupt instruction is placed in the main ladder program
(before the End instruction), enabling the interrupt. The interrupt remains
enabled until the program executes a Disable Interrupt instruction.