Setting For Sampling Processing/Averaging Processing - Mitsubishi Electric MELSEC A Series Manual

3. SPECIFICATIONS
3.7.2

Setting for sampling processing/averaging processing

(1) Digital value output in sampling processing and averaging processing
(a) Sampling processing
The analog values input to the channels are converted 1:1 to digital output
values. These digital output values are then stored in buffer memory.
(b) Averaging processing
The A68ADN does the A-D conversion for any channels which the PC CPU
has specified for averaging processing. Using a preset count or a preset
period of time, an average is calculated (excluding the minimum and
maximum values) and stored in buffer memory. If the specified processing
count is two or less, sampling processing is executed instead of averaging
processing.
When A-D conversion-enabled/disabled setting is made, data stored in the
work area is initialized.
POINTS
(1) When sampling processing is designated:
As the A68ADN's PC CPU scans each channel, the value appearing at
that instant is written to the buffer memory as a digital value. The timing of
this sampling depends on the number of A-D conversion-enabled
channels, and may be found by using the following formula:
(processing time) =
(number of A – D conversion – enabled channels) × 20 (ms/1 channel)
Example: When conversion-enabled is set for channels 1, 2, 3, 5, and 6:
Processing time = 5 × 20 = 100 (ms)
(2) Averaging processing by specifying time
(a) The setting time is in 10 ms units. Values less than 10 ms are round-
ed down.
Example: If 1234 ms is set, it is processed as 1230 ms.
(b) The number of times set time processing is done varies with the
number of A-D conversion-enabled channels.
Processing count =
Example: Number of A-D conversion-enabled channels = 4, Time setting = 8000 ms
8000 ÷ (4 × 20) = 100 times
(3) Averaging processing by specifying a number of counts
The time in which the average value by this processing is stored in the
buffer memory varies with the number of A-D conversion-enabled chan-
nels.
Processing time = (count setting) × (A-D conversion-enabled channels ×
Example: When A-D conversion-enabled is set for channels 1, 2, 3 and 4
50 × 4 × 20 = 4000 (ms)
(number of A – D conversion-enabled channels) × 20 (ms/channel)
Maximum conversion speed
20 (ms/channel)
Maximum conversion speed
3 − 15
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MELSEC-A
Maximum conversion
speed
Time setting