High Speed Counter [C]; Types And Device Numbers Of High Speed Counters - Mitsubishi Electric MELSEC-Q Structured Programming Manual

FXCPU Structured Programming Manual
[Device & Common]
2.7

High Speed Counter [C]

2.7.1

Types and device numbers of high speed counters

1. Types of high speed counters
The PLC main unit has built-in 32-bit high speed bidirectional counters (1-phase 1-counting, 1-phase 2-
counting and 2-phase 2-counting). These high speed counters are classified into the hardware type and the
software type according to the counting method.
Some high speed counters can be used together with an external reset input terminal and external start input
terminal (for counting start).
2. Classification of high speed counters according to the counting method
• Hardware counters :These types of counters execute counting using hardware, but are switched to
• Software counters : These types of counters execute counting through CPU interrupt processing.
→ For restriction of the response frequency depending on the total frequency, refer to Subsection
3. Types of high speed counters and input signal forms
The table below shows the types (1-phase 1-counting, 1-phase 2-counting and 2-phase 2-counting) and input
signals (waveforms) of high speed counters.
1-phase 1-counting input
1-phase 2-counting input
2-phase 2-counting
input
62
software counters depending on the operation condition.
→ For the condition handled as software counters, refer to Subsection 2.7.9.
It is necessary to use each software counter within restrictions of both the maximum
response frequency and the total frequency.
Input signal form
UP/DOWN
+1 +1 +1
UP
DOWN
Phase A
+1
+1
Phase B
Up-counting
+1 +1 +1 +1 +1
Phase A
Phase B
+1 +1 +1 +1
Up-counting
-1 -1 -1
Phase A
-1
-1
Phase B
Down-counting
-1 -1 -1 -1 -1
Phase A
Phase B
-1 -1 -1 -1
Down-counting
2 Devices in Detail
2.7 High Speed Counter [C]
Counting direction
The ON/OFF status of M8235 to M8245
specifies down-counting or up-counting.
ON: Down-counting
OFF: Up-counting
A counter executes up-counting or down-
counting as shown on the left.
The counting direction can be checked in
M8246 to M8250.
ON: Down-counting
OFF: Up-counting
A counter automatically executes up-
counting or down-counting according to
changes in the input status of the phase
A or B as shown on the left.
The counting direction can be checked in
M8251 to M8255.
ON: Down-counting
OFF: Up-counting
2.7.10.