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FX3S/FX3G/FX3GC/FX3U/FX3UC Series
Programming Manual - Basic & Applied Instruction Edition
13 High-Speed Processing – FNC 50 to FNC 59
13.7 FNC 56 – SPD / Speed Detection
Cautions
1. Input specifications of the input
• An input device X000 to X007 specified as cannot overlap the following functions or instructions:
- High-speed counter
- Input interrupt
- Pulse catch
- Pulse width/Pulse period
- DSZR instruction
- DVIT instruction
- ZRN instruction
• For one input, this instruction can only be used once.
• The maximum input frequency of turning the inputs X000 to X007 ON and OFF is shown below:
-FX
3S PLC
-FX
3G/FX3GC PLCs
-FX
3U/FX3UC PLCs
*1. When receiving pulses within the response frequency range of 50 k to 100 kHz, perform the following actions:
- Make sure that the wiring length is 5 m or less.
- Connect a bleeder resistor of 1.5 kΩ (1 W or more) to the input terminal, and make sure that the load
current in the open collector transistor output of the external equipment is 20 mA or more.
2. Occupied devices
1) When using the 16-bit operation
Three devices are occupied from a device specified in
*2
.
2) When using the 32-bit operation
Six devices are occupied from a device specified in
*2
.
*2. The value is updated by interrupt processing from the CPU, not every scan time (operation cycle) of the PLC.
3. When the value of the word device is changed while the SPD instruction is being
executed
.
When the value of the word device is changed while the SPD instruction is being executed, the operation varies
depending on the PLC model.
-FX
3U/FX3UC PLCs
The changed value of the word device is reflected on the operation at every scan time (operation cycle).
-FX
3S/FX3G/FX3GC PLCs
The changed value of the word device is not reflected on the operation at every scan time (operation cycle), and
the PLC operates using the value specified when execution of the SPD instruction started.
The PLC operates using the changed value after the command input of the SPD instruction is turned OFF once
and turned ON again.
Function change depending on the version
The function of the FNC 56 instruction varies depending on the PLC version shown in the table below.
Used input number Maximum input frequency
X000,X001 60 kHz
X002,X003,X004,X005 10 kHz
Used input number Maximum input frequency
X000,X001,X003,X004 60 kHz
X002,X005,X006,X007 10 kHz
Used input number
Maximum input frequency
FX3UC PLC
FX3U PLC
Main unit FX3U-4HSX-ADP
X000 to X005
100 kHz
*1
100 kHz
*1
200 kHz
X006,X007 10 kHz 10 kHz
Applicable version
Item Outline of function
FX3S FX3G FX3GC FX3U FX3UC
Ver. 1.00
or later
Ver. 1.00
or later
Ver. 1.40
or later
Ver. 2.20
or later
Ver. 2.20
or later
Addition of 32-bit instruction 32-bit operations (DSPD) are enabled.
S
1
S
1
D
D
S
2