Overview (Sequence Program); Introduction Of Convenient Functions; Convenient Functions For Input Processing - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
2.

Overview (Sequence Program)

This chapter explains the basic functions of FX
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 /FX /FX
3G 3U 3UC
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
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
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
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
received (except 1 and 4 edge count).
*2. Can only be connected to the FX
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.
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
however, the filter value can be changed in sequence programs.
*1. X000 to X007 in the FX
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.
PLCs have the following instruction functions.
*1
is used) in FX /FX
3U 3UC
*1
is used) in FX /FX
3U 3UC
PLC.
3U
/FX
3U 3UC
→ Related instruction: Refresh and filter adjust instruction REFF (FNC 51)
, FX -16M
3G 3U
2.1 Introduction of Convenient Functions
/FX /FX PLCs.
3G 3U 3UC
PLCs and up to 60 kHz in FX
PLCs and up to 30 kHz in FX
→ Related instructions: High speed counter compare;
HSCS (FNC 53), HSCR (FNC 54) and HSZ (FNC 55)
*2
, high speed pulses at up to 50 kHz can be
PLC.
→ FX
2N(C)
→ Related instruction: Refresh REF (FNC 50)
and FX -16M .
3UC
2 Overview (Sequence Program)
PLCs regardless of the
3G
PLCs.)
3G
-1HC high speed counter block
→ Refer to Section 36.7.
1
2
3
4
5
6
7
8
*1
,
9
10
25