794
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
35 Interrupt Function and Pulse Catch Function
35.5 Timer Interrupt (Interrupt in Constant Cycle)
5. Cautions
• Each pointer number (I6, I7 or I8) can be used only once.
• When M8056 to M8058 is set to ON in a program, a corresponding timer interrupt is disabled.
6. Program example
→
For program examples in which RAMP (FNC 67) or HKY (FNC 71) instructions are combined, refer
to Subsection 35.5.2.
In the program example shown below, data is added and the addition result is compared with the set value at
every 10 ms.
1) Program example
35.5.2
Examples of practical program (timer interrupt programs using applied instruction)
RAMP (FNC 67), HKY (FNC 71), SEGL (FNC 74), ARWS (FNC 75) and PR (FNC 77) instructions execute a
series of operations in synchronization with the scan time.
Because the total time may be too long or time fluctuation may cause a problem in these instructions, it is
recommended to execute these instructions at a constant time interval using the timer interrupt function.
When not using the timer interrupt function, use the constant scan mode.
Step
0
I610
Interrupt
pointer
When interrupt is
given at every 10 ms
M3
X001
FNC 04
EI
FNC 06
FEND
FNC 24
INC
FNC224
LD=
FNC 03
IRET
END
SET
M3
D0
K1000
D0
RST
M3
Interrupts are enabled by EI instruction.
The main program is described.
When M3 is set to ON, FNC 24 (INC)
instruction becomes valid.
The main program is finished by FEND
instruction.
"1" is added to the current value of D0 at
every 10 ms.
When the current value of D0 reaches
"1000", M3 is reset.
The current value of D0 is ramp data
which changes from "0" to "1000" in 10
seconds.
In the program example using FNC 67
(RAMP) instruction shown later, the ramp
data is made using a dedicated applied
instruction.