798
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
35 Interrupt Function and Pulse Catch Function
35.7 Pulse Catch Function [M8170 to M8177]
6. Cautions
1) Pointer number
Pointer numbers cannot overlap with each other.
2) Disabling interrupts
When the special auxiliary relay M8059 is set to ON in a program, all counter interrupts are disabled.
35.7
Pulse Catch Function [M8170 to M8177]
When the input relay X000 to X007 turns ON from OFF after the FNC 04 (EI) instruction is executed, the
special auxiliary relay M8170 to M8177 is set for interrupt processing.
1. Assignment of input numbers and special auxiliary relays
*1.
Cleared when the PLC mode is changed from STOP to RUN.
2. Program example
*1.
When using the pulse catch function at 5
µ
s 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 k
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.
Pulse catch input
Pulse catch relay
X000
M8170
*1
X001
M8171
*1
X002
M8172
*1
X003
M8173
*1
X004
M8174
*1
X005
M8175
*1
X006
M8176
*1
X007
M8177
*1
M8170
X002
Reset input
RST
M8170
Y000
When the rising edge of X000 is detected,
M8170 is set as interrupt.
The pulse catch result is reset.
FNC 04
EI
Step
0
Input pulse width
(shown below)
EI
X000(Input)
M8170
X002(Reset)
[X000 to X005]: 5
µ
s or more
*1
[X006 and X007]: 50
µ
s or more