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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.8 High Speed Counter [C] (FX3G PLCs)
1
Introduction
2
Overview
3
Instruction
List
4
Devices
in Detail
5
Specified the
Device &
Constant
6
Before
Programming
7
Basic
Instruction
8
FNC00-FNC09
Program Flow
9
FNC10-FNC19
Move & Compare
10
FNC20-FNC29
Arith. & Logic
Operation
4.8 High Speed Counter [C] (FX3G PLCs)
4.8.1 Types and device numbers of high speed counters
1. Types of high speed counters
The main unit has built-in 32-bit high speed bi-directional counters (1-phase 1-count, 1-phase 2-count and 2-phase 2-
count). Some high speed counters are capable of using an external reset input terminal and an external start input
terminal (for counting start).
2. Classification of high speed counters according to counting method
These types of counters execute counting as CPU interrupt processing.
Observe both the restriction in response frequency for each counter and the restriction in total frequency when using
high speed counters.
→ For the limitation of response frequency depending on the total frequency,
refer to Subsection 4.8.7.
3. Types of high speed counters and input signal forms
The table below shows the types (1-phase 1-count, 1-phase 2-count and 2-phase 2-count) and input signals
(waveforms) of high speed counters.
4. Cautions on counterpart equipment connected to high speed counter inputs
General-purpose inputs X000 to X007 are used for high speed counter inputs. An encoder
*1
adopting the output
method shown in the table below can be connected depending on the connected terminal.
Encoders adopting the voltage output method and absolute encoders cannot be connected to high speed counter
inputs.
→ For the wiring, refer to the Hardware Edition of the main unit.
*1. A rotary encoder adopting the output method shown above may not operate correctly depending on the
electrical compatibility. Check the specifications before connecting an encoder.
Input signal form Counting direction
1-phase
1-count input
Down-count or up-count is specified by
turning on or off M8235 to M8245.
ON: Down-counting
OFF: Up-counting
1-phase
2-count input
A counter executes up-count or down-
count as shown on the left.
The counting direction can be checked
with M8246 to M8250.
ON: Down-counting
OFF: Up-counting
2-phase
2-count input
A counter automatically executes up-
count or down-count according to
changes in the input status of the A/B
phase as shown on the left.
The counting direction can be checked
with M8251 to M8255.
ON: Down-counting
OFF: Up-counting
Output method of encoder which can be directly connected to input
terminal in main unit
Open collector transistor output method compatible with 24V DC
UP/DOWN
UP
DOWN
+1 +1 +1
−1 −1 −1
B phase
A
phase
+1
+1
Up-counting
A phase
B phase
−1
−1
Down-counting