YOKOGAWA FA-M3V e-RT3 Plus, Hardware Manual

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A2-29
IM 34M06C11-01E
- Interrupt Function
If the interrupt function is selected, the F3XH04-3N module continues to hold its
input on for the duration of 512µs once it detects an off-to-on transition in the input.
The interrupt program therefore may not be executed if an input pulse shorter than
512µs is used as the interrupt signal. If a module that responds very quickly to a
change in the input signal, like this F3XH04-3N module, is used as the means for
inputting interrupt signals, the CPU module will continue to run the interrupt program
for an input of consecutive high-speed pulses and fail to run its regular programs. To
avoid this, the F3XH04-3N module is designed to hold the given input signal for a
specific length of time once it detects a pulse in order to prohibit itself from detecting
any subsequent pulses. This function thus prevents the CPU module from running
the interrupt program repeatedly.
The timing diagram of the interrupt function is show below.
CPU processing
Interrupt processing
Interrupt input
ꞏ Shorter than
50

s
ꞏ Unreadable
ꞏ Longer than
50

s
ꞏ Readable
Input holding time
(512

s)
Sampling
Module signal after
passing
through the filter
Sampling is suspended and the
signal is held for specified period
after detection of edge in off-to-on
transition.
Sampling resumed after the
hold time is up.
1 scan
FA020510.VSD
Figure A2.13 Behavior when an Interrupt Occurs
Note
Do not allow the input relays of any single F3XH04-3N module to be shared by more
than one CPU module. Otherwise, the pulse-capture or interrupt function may not work
correctly. (This is still applicable even if two or more CPU modules share a relay having
a different number.)