25
FX
3G
/FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
2 Overview (Sequence Program)
2.1 Introduction of Convenient Functions
1
Int
roduct
ion
2
O
ver
view
3
In
str
uc
tion
Li
st
4
D
evices
in D
etail
5
Spec
ified t
he
D
evice &
C
onst
ant
6
Bef
ore
Pr
ogr
am
m
ing
7
B
asic
In
st
ru
ct
io
n
8
FN
C
00-FN
C
09
P
rogr
am
F
low
9
FN
C
10
-FN
C
19
Mo
ve
&
Co
mp
are
10
FNC2
0-F
NC2
9
Ar
ith.
&
Logic
O
per
ation
2.
Overview (Sequence Program)
This chapter explains the basic functions of FX
3G
/FX
3U
/FX
3UC
PLCs.
This chapter includes not only the features of PLCs but also introduction of representative functions,
parameters and memory to utilize the functions of PLCs. Read this chapter before designing sequences.
2.1
Introduction of Convenient Functions
FX
3G
/FX
3U
/FX
3UC
PLCs have the following instruction functions.
2.1.1
Convenient functions for input processing
1. "High speed counter" function of one phase or two phases for counting high speed inputs
One-phase high speed counters can execute counting at up to 100 kHz (or 200 kHz when a special high
speed input adapter
*1
is used) in FX
3U
/FX
3UC
PLCs and up to 60 kHz in FX
3G
PLCs regardless of the
operation time because they process high speed pulses from specific input relays as interrupts.
(Two-phase high speed counters can execute counting at up to 50 kHz (or 100 kHz when a special high
speed input adapter
*1
is used) in FX
3U
/FX
3UC
PLCs and up to 30 kHz in FX
3G
PLCs.)
The counting result can be immediately handled as high speed counter output interrupts by specific program
processing and high speed counter counted values by comparison instructions dedicated to high speed
counters.
*1.
Can only be connected to the FX
3U
PLC.
→
Related instructions: High speed counter compare;
HSCS (FNC 53), HSCR (FNC 54) and HSZ (FNC 55)
If the number of high speed counters is insufficient, special extension equipment (high speed counter
blocks) can be connected.
By extending hardware counters in the high speed counter block
*2
, high speed pulses at up to 50 kHz can be
received (except 1 and 4 edge count).
*2.
Can only be connected to the FX
3U
/FX
3UC
PLC.
→
FX
2N(C)
-1HC high speed counter block
2. "I/O refresh" function for receiving the latest input information
The input terminal information of the PLC in the batch refresh method is input all at once by the input image
memory before step 0. The output information is output at one time when END instruction is executed.
I/O refresh instruction can get the latest input information and immediately output the operation result during
sequence operation.
→
Related instruction: Refresh REF (FNC 50)
3. "Input filter adjustment" function for changing the time constant of input relays
Input relays in the PLC are equipped with a C-R filter of approximately 10 ms as countermeasures against
chattering and noise in input signals. Because a digital filter is adopted for the input relays X000 to X017
*1
,
however, the filter value can be changed in sequence programs.
→
Related instruction: Refresh and filter adjust instruction REFF (FNC 51)
*1.
X000 to X007 in the FX
3G
, FX
3U
-16M
and FX
3UC
-16M
.
4. "Pulse catch" function
The pulse catch function is provided as a method to receive short-time pulse signals.
The pulse catch function monitors signals from specific input relays, and sets special auxiliary relays in the
interrupt processing as soon as signals are input.
The pulse catch function can be used in a wide range of applications because even narrow pulses can be
easily received.
When complicated operations should be processed with high priority as interrupt by using specific trigger
signals, the "interrupt" function described later is suitable.
→
Refer to Section 36.7.