162
FX
3UC
Series Programmable Controllers
User’s Manual - Hardware Edition
5 Input Specifications and External wiring
5.5 High-speed Counters (C235 to C255)
1) Calculation of overall frequency
The overall frequency is calculated using the above table according to the high-speed comparison
instructions being used in the program.
Overall frequency
≥
Sum of "response frequency of high-speed counter
×
Magnification for
calculation of overall frequency"
2) Example of calculation
When only the HSZ instruction is used six times in a program, the frequency is calculated by the formulas
shown in the "Only HSZ instruction" column in the above table.
2. When FX
3U
/FX
3UC
Series special function blocks and analog special adapters are used
Examples of calculation are given in the heavy-line frame.
*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) cannot count signals of 10 kHz or more.
High-speed counter No. to be
used
Input
frequency
Calculation of max.
response frequency
Magnification
for
calculation of
overall
frequency
Instruction
to be used
C237
Operation as
software counter
30kHz
40 - 6(times) = 34kHz
×
1
HSZ instruc-
tion is used
six times.
C241
Software counter
20kHz
40 - 6(times) = 34kHz
×
1
C253 (OP)
[4 edge count]
4kHz
{
40 - 6(times)
}
/ 4 = 8.5kHz
×
4
Counter type
Counter
Nos.
Software
counters
with
HSCS,
HSCR,
HSZ or
HSCT
instruction
*1
Magni-
ficatio
n for
calcu-
lation
of
overall
frequ-
ency
Response frequency and overall frequency depending on
instructions being used
Neither HSZ nor
HSCT instruction
Only HSCT
instruction
Only HSZ instruction
Both HSZ and HSCT
instructions
Max.
response
frequency
(kHz)
Overall
frequency
(kHz)
Max.
response
frequency
(kHz)
Overall
frequency
(kHz)
Max.
response
frequency
(kHz)
Overall
frequency
(kHz)
Max.
response
frequency
(kHz)
Overall
frequency
(kHz)
1-phase
1-count input
C241
C242
C243
C244
C245
C235
C236
C237
C238
C239
C240
×
1
30
60
25
50
30 -
(number of
instruc-
tions)
*2
50 - 1.5
×
(number of
instruc-
tions)
25 -
(number of
instruc-
tions)
*2
50 - 1.5
×
(number of
instruc-
tions)
−
C244(OP)
C245(OP)
×
1
10
10
1-phase
2-count input
C247
C248
C249
C250
C246
C248(OP)
×
1
30
25
2-
phase
2-
count
input
1 edge
count
C252
C253
(OP)
C254
C255
C251
C253
×
1
30
25
4 edge
count
×
4
7.5
6.2
(30 -
number of
instruc-
tions) / 4
(25 -
number of
instruc-
tions) / 4
1) The overall frequency is calculated as shown below since HSZ instruction is
used six times.
Overall frequency = 80 - 1.5
×
6 = 71kHz
2) The sum of the response frequencies of the high-speed counters being
used is calculated as follows:
"30kHz
×
1[C237]" + "20kHz
×
1[C241]" + "4kHz
×
4[C253(OP)]" = 66kHz
≤
71kHz
Summary of Contents for FX3UC Series
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