Types Of Counting And Operations; Classification According To Counting Method; Types And Input Signal Forms; High-Speed Counter Device Notations - Mitsubishi FX3U SERIES User Manual

FX Series Programmable Controllers
3U
User's Manual - Hardware Edition
11.3

Types of Counting and Operations

The main unit has built-in 32-bit high speed bi-directional counters (1-phase 1-count input, 1-phase 2-count
input and 2-phase 2-count input). The high-speed counters are classified into hardware counters and
software counters according to the counting method.
For some high-speed counters, external reset input terminals or external start input terminals (start of
counting) can be selected.

11.3.1 Classification according to counting method

Classification
Hardware counters
Software counters

11.3.2 Types and input signal forms

The types and input signals (waveforms) of high-speed counters (1-phase 1-count input, 1-phase 2-count
input and 2-phase 2-count input) are shown below.
Type of counter
1-phase 1-count
input
1-phase 2-count
input
1 edge
count
2-phase
2-count
input
4 edge
count

11.3.3 High-speed counter device notations

The input terminal assignments for FX
combination with a special auxiliary relay.
This section classifies these high-speed counter devices under the following notations. Note that an "(OP)"
input cannot be programmed.
Standard Device
Numbers
C244
C245
Counting by hardware
They are switched to software counters under some working conditions.
Counting through interrupt handling by CPU
Each counter must be used within limitations on maximum response frequency and overall
frequency.
Input signal form
UP/
DOWN
+1 +1
UP
-1
DOWN
Phase A
+1 +1
Phase B
Up-counting
+1 +1 +1 +1 +1
Phase A
Phase B
+1 +1 +1 +1
Up-counting
3U
Switched Device
Numbers
C244(OP)
C245(OP)
11 Use of High-speed Counters (C235 to C255)
Details
Down-counting or up-counting is specified by
turning on or off M8235 to M8245.
ON: Down-counting
OFF: Up-counting
Up-counting or down-counting
The counting direction can be checked with
M8246 to M8250.
-1
ON: Down-counting
OFF: Up-counting
-1 -1
Automatic
Down-counting
according to change in input status of phase A/B
The counting direction can be checked with
-1 -1 -1 -1 -1
M8251 to M8255.
ON: Down-counting
OFF: Up-counting
-1 -1 -1 -1
Down-counting
PLC high-speed counters can be switched when used in
Standard Device
Numbers
C248
C253
11.3 Types of Counting and Operations
Counting direction
up-counting or down-counting
Switched Device
Numbers
C248(OP)
C253(OP)
11
12
13
14
15
16
17
18
19
20
185