100
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.7 High Speed Counter [C]
2) When special analog adapters and FX
3U
/FX
3UC
Series special function blocks/units in use
*1.
When an index register is added to a counter number specified in 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"
→
For a calculation example, see below.
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 blocks/units.
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 instruction)
÷
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 frequency of used high speed counters is as follows:
"30 kHz
×
1[C237]" + "20 kHz
×
1[C241]" + "4
×
4[C253(OP)]" = 66 kHz
≤
71 kHz
