Mitsubishi Electronics FX3G User Manual

FX

3S

/FX

3G

/FX

3GC

/FX

3U

/FX

3UC

 Series

Programming Manual - Basic & Applied Instruction Edition

24 Others – FNC181 to FNC189

FNC160

-F

NC1
69

R

eal
 T

ime C

lock
 

C

ontrol

FNC17

0-F

NC
179

E

xternal D

evice

FNC

180

Alternate 

Instructions

FN

C181-

FNC18

9

O

thers

FNC190

-F

NC1
99

Bl

oc

k D
ata

 

Op
er

ation

FNC20

0-F

NC209

C

har

ac

te

r S

trin

g 

Con
tro

l

FNC2
10-
FNC21

9

Dat
a 

Operati

on 3

FNC220

-F

NC2
49

Da

ta 

C

omp
ari

son

FNC25

0-F

N

C

269

D

ata T

abl
e 

Operation

FNC2

70-
FNC276

Ex

-Dev

ice

1) High-speed counter current value update timing

When a pulse is input to an input terminal for a high-speed counter (C235 to C255), the high-speed counter
executes up-counting or down-counting.
If the current value of a high-speed counter is handled in an applied instruction such as the normal MOV
instruction, the current value is updated at the timing shown in the table below. As a result, it is affected by the
program scan time.

By using DHCMOV instruction, the current value can be updated and transferred when it is executed.

2) Effect of DHCMOV instruction

• By using both input interrupt and DHCMOV instruction, the current value of a high-speed counter can be 

received at the rising edge or falling edge of an external input (at reception of input interrupt).

→ Refer to the Program example 2.

• When DHCMOV instruction is used just before a comparison instruction (CMP, ZCP or comparison contact 

instruction), the latest value of a high-speed counter is used in comparison. The following points must be kept 
in mind when using the DHCMOV command.
- When the current value of a high-speed counter is compared using CMP, ZCP or comparison contact 

instruction (not using a designated high-speed counter comparison instruction), a hardware counter does 
not change into a software counter.

→ For the condition in which a hardware counter is handled as a software counter, refer to Subsection 4.8.9.

- When the number of high-speed software counter comparison instructions is reduced, the total frequency 

limitation is decreased.

→ For the limitation in software counters by the total frequency, refer to Subsection 4.8.10.

- When it is necessary to execute comparison and change an output contact (Y) as soon as the current value 

of a high-speed counter changes, use a designated high-speed counter comparison instruction (HSCS, 
HSCR or HSZ).

- DHCMOV instruction can be used as many times as necessary.

When programming DHCMOV instruction in an input interrupt program, the following points should be observed.
For assignment of pointers for input interrupt and inputs, refer to the table shown in 5) below.
1) Program EI (FNC 04) and FEND (FNC 06) instructions in the main program. They are necessary to execute an

input interrupt program.

→ For EI (FNC 04) and FEND (FNC 06) instructions, refer to Section 8.5 and Section 8.7.

2) When programming DHCMOV instruction in the 1st line in an input interrupt program, make sure to use the

pattern program shown below. Make sure to use the command contact M8394. Do not add, change, or delete this
pattern program when writing during RUN. Interrupt programs may not operate normally.

Hardware counter

When OUT instruction for the counter is executed

Software counter

Every time a pulse is input

FNC 03

IRET

M8394

n

FNC189

DHCMOV

I

Pattern program for using the
DHCMOV instruction in an interrupt
program

Program to be processed as input
interrupt

S

D