Mitsubishi FX3U SERIES User Manual page 202

FX Series Programmable Controllers
3U
User's Manual - Hardware Edition
1) Calculation of overall frequency
The overall frequency is calculated by the high-speed comparison instruction used in the program based
on the above table.
Overall frequency ≥ Sum of "response frequency of high-speed counter × Magnification for
calculation of overall frequency"
2) Example of calculation
When only 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.
High-speed counter No. to be
C237
C241
C253(OP)
[
4 edge count
1) The overall frequency is calculated as shown below because 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 used is
calculated as shown below.
"30kHz × 1[C237]" + "20kHz × 1[C241]" + "4kHz × 4[C253(OP)]" = 66kHz ≤ 71kHz
2. When FX Series special function units/blocks and analog special adapters are used
3U
Software
counters
with
HSCS,
Counter
Counter type HSCR,
Nos.
HSZ or
HSCT
instructio
n *1
C235,
C241,
C236,
C242,
C237,
C243,
C238,
1-phase
C244,
C239,
1-count input
C245
C240
C244(OP),
−
C245(OP)
C247,
1-phase C248, C246,
2-count input C249, C248(OP)
C250
1 edge
2- count C252,
phase C253
C251,
2- (OP),
C253
4 edge
count C254,
count
input C255
*1. When an index register is added to a counter number specified by 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.
196
used frequency
Operation as
software counter
Software counter
]
Magni-
fication
for
Neither HSZ nor
calcu-
HSCT instruction
lation
Max.
of
response
overall
frequency
frequency
frequ-
(kHz)
ency
×
30
1
×
10
1
×
1 30
×
1 30
×
7.5
4
11 Use of High-speed Counters (C235 to C255)
11.9 Calculation of Response Frequency and Overall Frequency
Input Calculation of max.
response frequency
30kHz 40 - 6(times) = 34kHz
20kHz 40 - 6(times) = 34kHz
{40 - 6(times)} / 4 = 8.5kHz
4kHz
Response frequency and overall frequency depending on
conditions of instruction to be used
Only HSCT
instruction
Max.
Overall Overall
response
frequency
frequency
(kHz) (kHz)
(kHz)
25
10
60 50
25
25
6.2
Magnification
for
calculation of
overall
frequency
×
1
×
1
×
4
Both HSZ and HSCT
Only HSZ instruction
instructions
Max. Max.
Overall
response response
frequency
frequency frequency
(kHz)
(kHz) (kHz)
30 - 25 -
(number of (number of
instruc- instruc-
×
50 - 1.5
tions) tions)
(number of
*2 *2
instruc-
tions)
(30 - (25 -
number of number of
instruc- instruc-
tions) / 4 tions) / 4
Instruction
to be used
HSZ instruc-
tion is used
six times.
Overall
frequency
(kHz)
×
50 - 1.5
(number of
instruc-
tions)