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Analog Input Functions and Operating Procedures Section 3-6
3-6-3 Mean Value Processing
The Analog Input Unit can compute the mean value of the conversion values
of analog inputs that have been previously sampled. Mean value processing
involves an operational mean value in the history buffers, so it has no effect on
the data refresh cycle. (The number of history buffers that can be set to use
mean value processing is 2, 4, 8, 16, 32, or 64.)
When “n” number of history buffers are being used, the first conversion data
will be stored for all “n” number of history buffers immediately data conversion
has begun or after a disconnection is restored.
When mean value processing is used together with the peak value hold func-
tion, the mean value will be held.
To specify whether or not mean value processing is to be used, and to specify
the number of history buffers for mean data processing, use a Programming
Device to make the settings in D (m+2) to D (m+9) as shown in the following
table. (With the CJ1W-AD041-V1, make the settings in D (m+2) to D (m+5).)
For the DM word addresses, m = D20000 + (unit number × 100)
Note When DM Area settings have been carried out using a Programming Device,
be sure to either cycle the power supply to the PLC, or turn ON the Special
I/O Unit Restart Bit. The contents of the initial settings in the DM Area will be
transferred to the Special I/O Unit when the power is turned ON or the Special
I/O Unit Restart Bit is turned ON.
The history buffer moving average is calculated as shown below. (In this
example, there are four buffers.)
Conversion data
Buffer 1
Buffer 2
Buffer 3
Buffer 4
Buffer n
(Mean value
processing)
Conversion value
(Values stored in
CIO words n+1 to
n+8)
(Discarded)
DM Area
word
Function Set value
D (m+2) Input 1 mean value processing 0000: Mean value processing with 2 buffers
0001: No mean value processing
0002: Mean value processing with 4 buffers
0003: Mean value processing with 8 buffers
0004: Mean value processing with 16 buffers
0005: Mean value processing with 32 buffers
0006: Mean value processing with 64 buffers
D (m+3) Input 2 mean value processing
D (m+4) Input 3 mean value processing
D (m+5) Input 4 mean value processing
D (m+6) Input 5 mean value processing
D (m+7) Input 6 mean value processing
D (m+8) Input 7 mean value processing
D (m+9) Input 8 mean value processing
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