173
FX3G/FX3U/FX3GC/FX3UC Series
Programming Manual - Basic & Applied Instruction Edition
6 What to Understand before Programming
6.5 General Rules for Applied Instructions
1
Introduction
2
Overview
3
Instruction
List
4
Devices
in Detail
5
Specified the
Device &
Constant
6
Before
Programming
7
Basic
Instruction
8
FNC00-FNC09
Program Flow
9
FNC10-FNC19
Move & Compare
10
FNC20-FNC29
Arith. & Logic
Operation
6.5.5 Limitation in the number of instructions and limitation in simultaneous instruction
instances
Limitation in the number of instructions
Some applied instructions can only be used up to the specified number of times.
When using above instructions beyond the allowable number of times of use
For instructions whose operands allow indexing, device numbers and numeric values in such instructions can be
changed by index registers.
By indexing, when driving multiple instances simultaneously is not required, such instruction can be used as if they
were used beyond the allowable number of times.
→ Refer to "Subsection 5.7.3. Indexing example for instruction with limited number of use.".
Limitation in simultaneous instances of instructions
Some applied instructions can be programmed two or more times, but the number of simultaneous instances is
limited.
Even in instructions not shown below, if two or more instructions are driven at the same time for the same I/O number,
it is regarded as double outputs. In some combinations of instructions, the operation may be disrupted, or the
instructions cannot be executed.
For details, refer to the caution described in each instruction page.
For combinations of instructions, refer to "6.4 Mutual Relationship Among Program Flow Control Instructions".
1. Positioning instructions
Do not drive FNC 57 (PLSY), FNC 58 (PWM), FNC 59 (PLSR), FNC150 (DSZR), FNC151 (DVIT), FNC156 (ZRN),
FNC157 (PLSV), FNC158 (DRVI) and FNC159 (DRVA) instructions at the same time for the same output number.
2. High-speed processing instructions
•FX3U/FX3UC PLCs
In FNC 53 (HSCS), FNC 54 (HSCR) and FNC 55 (HSZ) instructions (including FNC280 (HSCT) instruction), make
sure that up to 32 instructions are driven at the same time. [FNC280 (HSCT) instruction can only be used once.]
Note that "FNC280 (HSCT) instruction", "table high-speed comparison mode of FNC 55 (HSZ) instruction)" and
"frequency control mode of FNC 55 (HSZ) instruction" can each only be used once.
•FX3G/FX3GC PLCs
The FNC 53 (HSCS), FNC 54 (HSCR) and FNC 55 (HSZ) instructions can be driven up to 6 times in total at the
same time.
3. External device communication instructions
• In FNC 80 (RS) and FNC 87 (RS2) instructions, do not drive two or more instructions at the same time for the same
port.
• It is impossible to combine and use "FNC 80 (RS), FNC 87 (RS2)", "FNC270 (IVCK) to FNC275 (IVMC)", "FNC300
(FLCRT) to FNC305 (FLSTRD)" instructions for the same port.
• In FNC270 (IVCK) to FNC275 (IVMC) instructions, two or more instructions can be driven at the same time for the
same port.
Instruction name
Allowable number of times of
use
Remarks
FNC 52 (MTR) 1 MTR instruction can only be used once in program.
FNC 56 (SPD) 8 (1 instruction/1 input or less)
Pay attention so that this instruction does not overlap the input numbers of in DVIT
instruction, DOG inputs in ZRN instruction, zero point signal in DSZR instruction,
input interrupt numbers and high-speed counter input numbers.
FNC 60 (IST) 1 −
FNC 69 (SORT) 1 −
FNC 70 (TKY) 1 −
FNC 71 (HKY) 1 −
FNC 75 (ARWS) 1 −
FNC 77 (PR) 2 PR instruction can only be used twice in a program.
FNC149 (SORT2) 2 −
FNC186 (DUTY) 5 (1 instruction/1 input or less) −
FNC280 (HSCT) 1 −
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