High Speed Counter [C] (Fx 3G Plcs); Types And Device Numbers Of High Speed Counters - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
4.8 High Speed Counter [C] (FX
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.
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.
1-phase
1-count input
1-phase
2-count input
2-phase
2-count input
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
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.
Output method of encoder which can be directly connected
to input terminal in 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.
PLCs)
3G
→ For the limitation of response frequency depending on the total frequency,
Input signal form
UP/DOWN
+1 +1 +1
UP
DOWN
A phase A phase
+1 +1
B phase B phase
Up-counting
→ For the wiring, refer to the Hardware Edition of the main unit.
4.8 High Speed Counter [C] (FX3G PLCs)
Down-count or up-count is specified
by turning on or off M8235 to
M8245.
ON: Down-counting
OFF: Up-counting
A counter executes up-count or
down-count as shown on the left.
The counting direction can be
checked with M8246 to M8250.
−1 −1 −1
ON: Down-counting
OFF: Up-counting
A counter automatically executes
up-count or down-count according to
changes in the input status of the A/
−1 −1 B phase as shown on the left.
The counting direction can be
checked with M8251 to M8255.
Down-counting
ON: Down-counting
OFF: Up-counting
Open collector transistor output method compatible with 24V
DC
4 Devices in Detail
refer to Subsection 4.8.7.
Counting direction
*1
adopting the
123
1
2
3
4
5
6
7
8
9
10