A/D Conversion Method - Mitsubishi Electric NZ2EX2B-60AD4 User Manual

8.6

A/D Conversion Method

Set whether to perform sampling processing or averaging processing for each channel.
(1) Sampling processing
This processing performs A/D conversion on analog input values in sequence. The converted values at this time
are referred to as digital operation values.
For a main A/D converter module, digital operation values are stored into CH Digital operation value (RWr2 to
RWr5) at every sampling periods. For an extension A/D converter module, digital operation values are stored into
CH Digital operation value (RWr12 to RWr15) at every sampling periods.
The sampling period of the main A/D converter module and the extension A/D converter module depends on the
conversion speed setting and the number of conversion enabled channels. For details, refer to the following:
• Conversion Speed and Sampling Period ( Page 90, Section 8.5.1)
(2) Averaging processing
This processing performs averaging processing on digital operation values for each channel, storing the average
values into CH Digital operation value (RWr2 to RWr5, RWr12 to RWr15).
There are three types of averaging processing as follows:
• Time average
• Count average
• Moving average
(a) Time average
This processing performs A/D conversion for a set time and averages the total excluding the maximum and
minimum values, storing the average value into CH Digital operation value (RWr2 to RWr5, RWr12 to
RWr15).
The number of processing times varies depending on the sampling period.
Number of processing times (times) =
Ex.
The number of processing times assuming the following settings with no extension module connected
Number of channels used (number of channels where A/D conversion is enabled)
Conversion speed
Setting time
For the time average, the valid lower limit value to be set is given by: Minimum number of processing times, or
4 × Sampling period.
15
(4 0.4)
Nine times of measurement is performed to output the average value.
Item
= 9.375 (times) Rounded down to the nearest whole number
Setting time
Sampling period
Setting
4 channels (CH1 to CH4)
400μs/channel
15ms
CHAPTER 8 FUNCTIONS
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