24
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
2 Overview (Sequence Program)
2.1 Introduction of Convenient Functions
2.
Overview (Sequence Program)
This chapter explains the basic functions of 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
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 is used) without regard to the operation time because they process high speed pulses
from specific input relays as interrupts. (Two-phase counters can execute counting at up to 50 kHz (or 100
kHz when a special high speed input adapter is used).)
The counting result can be immediately handled by specific program processing as high speed counter
interrupt for outputs and counted values of high speed counters by comparison instructions dedicated to high
speed counters.
→
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, high speed pulses at up to 50 kHz can be
received (except 1 and 4 edge count).
→
FX
2N
-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 at one time by the input image
memory before operation in the 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
3U
-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 35.7.
