8 Interrupt Function and Pulse Catch Function
8.3 Input Interrupt (Interrupt Triggered by External Signal)
812
FXCPU Structured Programming Manual
(Basic & Applied Instruction)
4. Number and operation of (six) interrupt pointers
*1. The input numbers differ from one type of PLC to another.
FX
0, FX0S and FX0N PLCs: supports X000 to X003 only.
*2. Cleared when the PLC mode is changed from RUN to STOP.
5. How to disable each interrupt input
When either one among M8050 to M8055 is set to ON in a program, interrupts from the corresponding input
number are disabled.
(Refer to the above table for the correspondence.)
6. Cautions
1) Do not use an input two or more times.
Make sure that an input relay number used as an interrupt pointer is not used in high speed counters,
pulse catch functions and pulse density instructions which use the same input range.
2) Automatic adjustment of the input filter
When an input interrupt pointer I
0 is specified, the input filter of the input relay is automatically
changed to the input filter for high speed receiving.
Accordingly, it is not necessary to change the filter value using REFF instruction or special data register
D8020 (input filter adjustment).
The input filter of an input relay not being used as an input interrupt pointer operates at 10 ms (initial
value).
3) Pulse width of input interrupt
For executing input interrupt by an external signal, it is necessary to input the ON or OFF signal having
the duration shown in the table below or more.
For the FX
3U, FX3UC and FX3G PLCs
*1. When using the input filter at the filter value of 5 μs or when receiving a pulse whose response
frequency is 50 k to 100 kHz using a high speed counter, perform the following.
- Make sure that the wiring length is 5 m or less.
- Connect a bleeder resistor of 1.5 Ω (1 W or more) to an input terminal, and make sure that the load
current of the open collector transistor output in the counterpart equipment is 20 mA or more
including the input current in the main unit.
Input number
*1
Pointer number
Interrupt disable command
Interrupt at rising edge Interrupt at falling edge
X000 I001 I000
M8050
*2
X001 I101 I100
M8051
*2
X002 I201 I200
M8052
*2
X003 I301 I300
M8053
*2
X004 I401 I400
M8054
*2
X005 I501 I500
M8055
*2
PLC Input number Input filter value when "0" is set
FX3U, FX3UC X000 to X005
5μs
*1
FX3G
X000, X001, X003, X004 10μs
X002, X005 50μs
I 0
0:Interrupt at falling edge 1:Interrupt at rising edge
0 to 5 according to the inputs X000 to X005
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