Mitsubishi FX2-16E series, User Manual

Page: 216 / 520

208
FX
3U
Series Programmable Controllers
User’s Manual - Hardware Edition
11 Use of High-speed Counters (C235 to C255)
11.3 Types of Counting and Operations
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
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.
11.3.3 High-speed counter device notations
The input terminal assignments for FX
3U
PLC high-speed counters can be switched when used in
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.
Classification Details
Hardware counters
Counting by hardware
They are switched to software counters under some working conditions.
Software counters
Counting through interrupt handling by CPU
Each counter must be used within limitations on maximum response frequency and overall
frequency.
Type of counter Input signal form Counting direction
1-phase 1-count
input
Down-counting or up-counting is specified by
turning on or off M8235 to M8245.
ON:
Down-counting
OFF: Up-counting
1-phase 2-count
input
Up-counting or down-counting
The counting direction can be checked with
M8246 to M8250.
ON:
Down-counting
OFF: Up-counting
2-phase
2-count
input
1 edge
count
Automatic up-counting or down-counting
according to change in input status of phase A/B
The counting direction can be checked with
M8251 to M8255.
ON:
Down-counting
OFF: Up-counting
4 edge
count
Standard Device
Numbers
Switched Device
Numbers
Standard Device
Numbers
Switched Device
Numbers
C244 C244(OP) C248 C248(OP)
C245 C245(OP) C253 C253(OP)
UP/
DOWN
UP
DOWN
+1 +1
-1 -1
Phase A
Phase B
+1 +1
Up-counting
-1 -1
Down-counting
Phase A
Phase B
+1
Up-counting
+1 +1 +1 +1
+1 +1 +1 +1
-1
Down-counting
-1 -1 -1 -1
-1 -1 -1 -1