A/D Conversion Methods - Mitsubishi Q64AD-GH User Manual

3 SPECIFICATIONS

3.2.1 A/D conversion methods

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(1) Sampling processing
A/D conversion is performed successively for the analog input value, and the
converted digital output values are stored in the buffer memory.
The conversion speed is 10ms regardless of the number of conversion enabled
channels.
(2) Averaging processing
(a) Time averaging
A/D conversion is made for the preset period of time, the sum of values other
than the maximum and minimum values is averaged, and the result is stored
into the buffer memory.
The processing count within the set time is uniform independently of the
number of used channels (number of channels set for A/D conversion enable).
Processing count = set time/10 (times)
[Example] When the averaging processing time is set to 42ms
42/10 = 4.2 (times) ... Fractional portion is dropped.
(b) Count averaging
A/D conversion is made the preset number of times, the sum of values other
than the maximum and minimum values is averaged, and the result is stored
into the buffer memory.
The time when the count-based average value is stored into the buffer
memory is uniform independently of the number of used channels (number
of channels set for A/D conversion enable).
Processing time = set count
[Example] When the averaging processing count is set to 5 times
5
(c) Move averaging
The specified count of digital output values imported per sampling time are
averaged to find a value, which is then stored into the buffer memory.
Since average processing is performed with data shifted per sampling, the
most recent digital output value is available.
Move averaging processing at the preset count of 4 times
A/D conversion
value
64000
2)
1)
32000
0
Data transition inside buffer memory
First storage
1)+2)+3)+4)
10 (ms)
10 = 50 (ms)
Sampling time
3) 4)
5)
6)
7)
A/D conversion completed flag ON
Second storage
2)+3)+4)+5)
4 4
8) 9)
12)
10) 11)
First storage
Second storage
Third storage
Time [ms]
Third storage
3)+4)+5)+6)
4
MELSEC-Q
Buffer memory
Digital output
value
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