Mitsubishi Electric MELSEC-Q Structured Programming Manual page 87

FXCPU Structured Programming Manual
[Device & Common]
• When special analog adapters and FX
Counter type
Following
software
counter
Software
combined with
counter
DHSCS, DHSCR,
DHSZ or DHSCT
instruction
C241, C242, C235, C236,
C243, C244, C237, C238,
1-phase
C245 C239, C240
1-counting
input
C244(OP),
-
C245(OP)
1-phase
C247, C248,
2-counting C246, C248(OP)
C249, C250
input
1-
edge
2-
count-
phase C252,
ing
2- C253(OP),
C251, C253
count- C254,
4-
ing C255
edge
input
count-
ing
*1. When index registers are added to a counter number specified by the DHSCS, DHSCR, DHSZ or
DHSCT instruction, all hardware counters switch to software counters.
*2. High speed counters C244 (OP) and C245 (OP) can count at up to 10 kHz.
• Calculation of the total frequency
Total frequency ≥ Sum of "Response frequency of high speed counter × Magnification for calculating total
frequency"
• Calculation example
When only the DHSZ instruction is used 6 times in a program, the total frequency is calculated as follows in
accordance with the columns for "When only DHSZ instruction is used" shown in the table above.
This calculation example is provided for a system configuration not including special analog adapters and
FX /FX Series special function blocks/units.
3U 3UC
Used high speed counter No.
C237
C241
C253(OP)
[4-edge counting]
1) The total frequency is calculated as follows because the DHSZ 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
calculated as follows:
{30kHz×1[C237]} + {20kHz×1[C241]} + {4kHz×4[C253(OP)]} =66kHz ≤ 71kHz
/
3U 3UC
Response frequency and total frequency according to instructions used
When DHSZ and
DHSCT instructions
are not used
Maximum
Total
response
frequency
frequency
(kHz)
*1
(kHz)
×1
30
×1
10
×1
30
60
×1
30
×4
7.5
Input
frequency
Operates as software
30kHz
counter.
20kHz
Software counter
4kHz
Series special function blocks/units are connected
When only DHSCT When only DHSZ
instruction is used instruction is used
Maximum Maximum
Total
response response
frequency
frequency frequency
(kHz)
(kHz) (kHz)
25
10 30 - (Num-
ber of times
of using
25
instruc-
tions)
50
25
(30 - Num-
ber of times
6.2 of using
instruc-
tions) / 4
Maximum response
frequency calculation
40 - 6 (times) = 34 kHz
40 - 6 (times) = 34 kHz
{40 - 6 (times)} / 4 = 8.5 kHz
2 Devices in Detail
2.7 High Speed Counter [C]
When both DHSZ and
DHSCT instructions
are used
Maximum
Total Total
response
frequency frequency
frequency
(kHz) (kHz)
(kHz)
25 - (Num-
ber of times
of using
50 - 1.5 × 50 - 1.5 ×
instruc-
(Number of (Number
*2 *2
times of tions) of times of
using using
instruc- instruc-
tions) tions)
(25 - Num-
ber of times
of using
instruc-
tions) / 4
Magnification for
Used
calculating total
instruction
frequency
×1
DHSZ instruc-
×1
tion × 6 times
×4
1
2
3
4
5
6
7
85