ISPSoft User Manual

Chapter 5 Program Organization Units and Tasks
• Hardware configuration
In this example, the CPU module AHCPU530-EN, the digital I/O module AH16AP11R-5A, and the
four-slot main backplane AHBP04M1-5A are used. (The hardware configuration here is the same
as the hardware configuration in chapter 4.)
• Planning a program
In this example, a timed interrupt is triggered every 25 milliseconds, and time intervals are
measured through a program. In the figure below, Timed Interruption (0) is triggered every 25
milliseconds, and the value in the 32-bit register (D1, D0) increases by one whenever Timed
Interruption (0) is triggered. As long as the PLC keeps running, Timed Interruption (0) is
triggered every 25 milliseconds, and the value in the 32-bit register (D1, D0) increases by one
whenever Timed Interruption (0) is triggered. Users can calculate the time for which the PLC has
run by reading the value in (D1, D0). For example, if the value in (D1, D0) is 10, the time for which
the PLC has run is 250 milliseconds (10x25 ms).
After the START button is pressed, the present value in (D1, D0) will be transferred to (D3, D2),
and the value in (D1, D0) will increase. After the present value in (D1, D0) is transferred to (D3,
D2), the value in (D3, D2) will remain unchanged. Users can calculate the time which has elapsed
since the START button was pressed by subtracting the value in (D3, D2) from the value in (D1,
D0). The value gotten is stored in (D5, D4).
Time when the START button is pressed
Time having elapsed since the
START button was pressed
Time for which the PLC has run
A timed interrupt in an AH500 CPU module is illustrated with the example in this section. The
instructions TKON and TKOFF are also illustrated with the example in this section. Five POUs are
created. The functions of the POUs are described below.
POU name
Function
The value in the 32-bit register (D1, D0) increases by one every 25
INT_Timer
milliseconds. (The POU is assigned to Timed Interruption (0).)
Reset the flags M0 and M1, transfer the value 0 to the 32-bit registers (D1,
D0), (D3, D2), (D5, D4), and (D7, D6), and enable the interrupt.
Initialize During the first scan cycle, Cyclic (0) to which the POUs are assigned is
enabled, and Cyclic (1) to which Initialize is assigned is disabled. As a
result, Initialize is only executed during the first cycle.
Control
Time_CHK
Signal
When X0.0 is turned form OFF to ON, the operation flag M0 is set to ON,
and the value in (D1, D0) is transferred to (D3, D2). When X0.1 is turned
from OFF to ON, or when an overflow occurs, the operation flag M0 is reset.
Users can calculate the time which has elapsed since the START button
was pressed by subtracting the value in (D3, D2) from the value in (D1, D0).
The value gotten is stored in (D5, D4). If the value gotten is less than 0, the
overflow flag M1 is set to ON.
If the time which has elapsed is more than 30 seconds (25 ms x1200), or the
overflow flag M1 is ON, the alarm Y0.0 will be set to ON.
*. Please refer to AH500 Operation Manual and AH500 Programming Manual for more information about the
interrupts in an AH500 series CPU module and the related applied instructions.
• Creating the program
Please create a project for AHCPU530-EN.
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