Handling Functions Of Extension Flag; Limitation In Number Of Instructions - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
6.5.4

Handling functions of extension flag

In some applied instructions, the function can be extended by combining a specific special auxiliary relay
determined for each applied instruction. An example is explained below.
- When X000 turns ON, this instruction exchanges the
contents of D10 and D11 with each other.
- If M8160 has been driven before the XCH instruction
and the source and destination of the XCH instruction
are specified to the same device, high-order 8 bits and
low-order 8 bits are exchanged with each other inside
the device.
- For returning this XCH instruction to the normal XCH
instruction, it is necessary to set M8160 to OFF.
When using an instruction requiring the function extension flag in an interrupt program, program DI instruction
(for disabling interrupt) before driving the function extension flag, and program EI instruction (for enabling
interrupt) after turning OFF the function extension flag.
6.5.5

Limitation in number of instructions

Limitation in the number of instructions and limitation in simultaneous driving
Some applied instructions can be used only up to the specified number of times.
Instruction
name
FNC 52(MTR)
FNC53 (HSCS)
FNC54 (HSCR)
FNC55 (HSZ)
FNC 56(SPD)
FNC 60(IST)
FNC 69(SORT)
FNC 70(TKY)
FNC 71(HKY)
FNC 75(ARWS)
FNC 77(PR)
FNC149(SORT2)
FNC186(DUTY)
FNC280(HSCT)
*1. Total number of times that the FNC53 (HSCS), FNC54 (HSCR) and FNC55 (HSZ) instructions are
used
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 in instruction with limited number of use".
Allowable number
of times of use
1
*1
The allowable number of times of use is restricted only in FX
6
8 Pay attention so that this instruction does not overlap the input numbers of in
(1 instruction/1 input DVIT instruction, DOG inputs in ZRN instruction, zero point signal in DSZR
or less) instruction, input interrupt numbers and high speed counter input numbers.
1
1
1
1
1
2
2
5
(1 instruction/1 input
or less)
1
6 What to Understand before Programming
6.5 General Rules for Applied Instructions
X000
X000
Remarks
MTR instruction can only be used once in program.
−
−
−
−
−
PR instruction can only be used twice in a program.
−
−
−
FNC 17
D10 D11
XCHP
Function extension flag
M8160
for the XCH instruction
FNC 17
D10 D10
XCHP
Same number
M8160
PLCs.
3G
185
1
2
3
4
5
6
7
8
9
10