Справочник Пользователя для Mitsubishi Electronics FX5

19  BUILT-IN I/O FUNCTION
19.5  FX3-Compatible Pulse Catch Function

Displayed items

Parameters are enabled when the CPU module is powered ON or after a reset.

Operation of the FX3-compatible pulse catch function is explained below.

When the status of the input (X0 to X7) changes OFF

ON after execution of the EI instruction, a special relay (SM8170 to 

SM8177) is immediately set to ON by interrupt processing. Pulse catch operates even when an input interrupt is also set in 
duplicate with other functions. Note, however, that the pulse catch must be set with parameters.

■Examples of program

When the status of the X0 changes OFF

ON after execution of the EI instruction, SM8170 is immediately set to ON by 

interrupt processing. To capture input again, turn X2 ON to reset SM8170. (X0 is assumed to be set with parameters.)

■Operation diagram

An operation diagram of the above program example is shown below.

 • The FX3-compatible pulse catch function operates only when “Interrupt (Rising)” or “Interrupt (Rising) + Pulse Catch” is set 

with parameters.

 • To capture input again, the special relay that is set must be reset by the program. Accordingly, new input cannot be 

captured until the special relay that is set is reset.

 • The special relays for FX3-compatible pulse catch are cleared at STOP

RUN and a reset.

 • The FX3-compatible pulse catch function is executed regardless of the operations of the special relays for disabling 

interrupts.

General/Interrupt/Pulse 
Catch Setting

Set the function to be used.
Set to “Interrupt (Rising)” or “Interrupt (Rising) + Pulse Catch”.

• General-purpose Input
• Interrupt (Rising)
• Interrupt (Falling)
• Interrupt (Rising + Falling)
• Interrupt (Rising) + Pulse Catch

General-purpose 
Input

Reset input

RST

SM8170

X2

SM8170

Y0

X0

Y2

EI

It can be simultaneously used in a program.

SM8170

X0 (input)

X2 (reset)

Input pulse width

EI