Mitsubishi Electronics FX3G User Manual

Page of 964
127
FX
3S
/FX
3G
/FX
3GC
/FX
3U
/FX
3UC
 Series
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.8 High-Speed Counter [C] (FX3U/FX3UC PLC)
1
Introdu
ction
2
Ov
ervi
ew
3
Instruction 
Li
st
4
D
evices 
in Det
ai
l
5
Specifi
ed the
De
vice
 &
 
C
onst
ant
6
Bef
ore
 
Pr
og
ra
mmi
ng
7
Bas
ic 
Instruction
8
FN
C00-FN
C0
9
Program Fl
ow
9
FNC
10-FN
C19
Mov
e & Com
pare
10
FNC
20-FNC
29
Arith. & Lo
gi
Operati
on
2) When special analog adapters and FX
3U
/FX
3UC
 Series special function units/blocks are used
*1.
When an index register is added to a counter number specified by a HSCS, HSCR, HSZ or HSCT instruction,
all hardware counters are switched to software counters.
*2.
The high-speed counters C244 (OP) and C245 (OP) can count up to 10 kHz.
3. Calculation of the total frequency
Total frequency 
 Sum of "Response frequency of high-speed counter × Magnification for calculating total frequency"
4. Calculation example
When only HSZ instruction is used 6 times in a program, the total frequency and response frequency are calculated as 
follows in accordance with the columns for "When only HSZ instruction is used" shown above.
This calculation example is provided for a system configuration not including special analog adapters and FX
3U
/FX
3UC
 
Series special function units/blocks. 
Counter type
Magnifica-
tion for 
calculating 
total 
frequency
Response frequency and total frequency according to instruction use condition
Software 
counter
Following 
software 
counter with 
HSCS, HSCR, 
HSZ or HSCT 
instruction
*1
When HSZ and HSCT 
instructions are not 
used
When only HSCT 
instruction is used
When only HSZ 
instruction is used
When both HSZ and HSCT 
instructions are used
Maximum 
response 
frequency 
(kHz)
Total 
frequency 
(kHz)
Maximum 
response 
frequency 
(kHz)
Total 
frequency 
(kHz)
Maximum 
response 
frequency 
(kHz)
Total 
frequency 
(kHz)
Maximum 
response 
frequency 
(kHz)
Total 
frequency 
(kHz)
1-phase 
1-counting input
C241, C242,
C243, C244,
C245
C235, C236,
C237, C238,
C239, C240
×1
30
60
25
50
30 - (Num-
ber of 
instruc-
tion)
*2
50
1.5
×(Num
ber of 
instruc-
tion)
25-(Number 
of instruc-
tion)
*2
50
1.5
×(Num
ber of 
instruc-
tion)
C244(OP),
C245(OP)
×1
10
10
1-phase 
2-counting input
C247, C248,
C249, C250
C246,
C248(OP)
×1
30
25
2-
phase 
2-
count-
ing 
input
1 edge 
count
C252,
C253(OP),
C254,
C255
C251, C253
×1
30
25
4 edge 
count
×4
7.5
6.2
(30-Num-
ber of 
instruc-
tion) 
÷ 4
(25-Number 
of instruc-
tion) 
÷ 4
Used high-speed counter No.
Input 
frequency
Maximum response frequency 
calculation
Magnification for 
calculating total 
frequency
Used 
instruction
C237
Operates as
software counter
30 kHz
40 
− 6 (times) = 34 kHz
× 1
HSZ
instruction 
× 6 
times
C241
Software counter
20 kHz
40 
− 6(times) = 34 kHz
× 1
C253(OP)
[4 edge count]
4 kHz
{40 
− 6(times)} ÷ 4 = 8.5 kHz
× 4
1) The total frequency is calculated as follows because HSZ instruction is used 6 times:
    Total frequency       = 80 
− 1.5 × 6 = 71 kHz
2) The sum of the response frequencies of the high-speed counters
    being used is calculated as follows:
                     "30 kHz 
× 1[C237]" + "20 kHz × 1[C241]" + "4kHz × 4[C253(OP)]" = 66 kHz ≤ 71 kHz