A/D Conversion Method - Mitsubishi Electric MELSEC iQ-F FX5 User Manual

A/D conversion method

An A/D conversion method can be set for each channel.
Sampling processing
This function A/D converts analog input values and stores them in the digital output value and digital operation value every
sampling cycle.
The sampling cycle is "Conversion speed (80 s)  Number of A/D conversion enabled channels".
Whether to enable or disable the A/D conversion can be set for each channel. Disabling the A/D conversion
for unused channels reduces the A/D conversion cycles.
Conversion cycle that applies when the three channels get A/D conversion enabled
• 80  3 = 240 (s)
The conversion cycle is 240 (s).
Averaging processing
The digital output value is averaging processed for each channel, and averaged value is stored in the digital output value and
the digital operation value.
The following three types of averaging processing are provided.
• Time average
• Count average
• Moving average
■Time average
Executes A/D conversion for the set time and performs the averaging processing on the total value excluding the maximum
and minimum values. The averaged value is stored in the digital output value and the digital operation value.
The number of processing times within the set time changes depending on the number of channels where A/D conversion is
enabled.
Processing times (times)
*1 Values after the decimal point are omitted.
Ex.
The following table shows the processing times with the setting below.
Item
Number of channels where the A/D conversion is enabled
Setting time
2
= 6.25  6
(4 × 0.08)
Conversion is processed 6 times and the mean value is output.
The valid lower limit setting value for the time average is calculated by the formula "Minimum processing times
(4 times)  Number of A/D conversion enabled channels  Conversion speed".
1 FX5-4AD
28
1.4 Functions
*1
=
(Number of A/D conversion enabled channels × Conversion speed)
Setting time
Setting
Four channels (CH1 to CH4)
2 ms