Input Filter Adjustment [D8020] - Mitsubishi FX3U Series Programming Manual

FX /FX Series Programmable Controllers
3U 3UC
Programming Manual - Basic & Applied Instruction Edition

36.2.9 Input filter adjustment [D8020]

The inputs X000 to X017
value is set between 0 to 60 ms (in 1 ms steps) in special data register D8020. After PLC powers ON, D8020
is automatically set to K10 (10 ms).
Input
terminal
X000
*1
X017
*1. X000 to X007 in the FX
1. Program example for adjusting the input filter
When the program shown below is executed, the filter constant is changed to 0 ms.
Because the C-R filter is provided in the hardware, however, the filter constant is actually a value shown in
the table below when "0" is specified.
M8000
RUN monitor
Input number
X000 to X005
X006, X007
X010 to X017
When setting the input filter to "5 µs" or when receiving pulses whose response frequency is 50 k to
*1.
100 kHz using high speed counters, perform the following:
- Input wiring length should be 5 m (16' 4") or less.
- Connect a bleeder resistor (1.5 kΩ, 1/2 W) to an input terminal. The load current of the open
collector transistor output in the device on the other end should be 20 mA or more including the
input current of the PLC.
*2. X000 to X007 in the FX
• The input filter constant can be changed as many times as need in the user program.
• This input filter adjustment described here is not required when using high speed counter, input interrupt,
or pulse catch (M8170 to M8175) functions.
836
*1
have a digital filter circuit with a setting range of 0 to 60 ms. The digital filter setting
Filter
0ms
0
1ms
1
Determined by the contents of D8020 (initial value: 10)
10
Input refresh
10ms
Image
60ms
60
memory
-16M
3U
FNC 12
K 0 D8020
MOV
Input filter value when "0" is set
*2
-16M
3U
36 Operation of Special Devices (M8000 -, D8000 -)
36.2 Supplement of Special Devices (M8000 - and D8000 -)
*1
5µs
50µs
200µs