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B-30
5 Buffer Memory (BFM)
5.4 Buffer Memory Details
FX
3G
/FX
3U
/FX
3UC
 PLC User's Manual - Analog Control Edition
FX
3U
-4AD/FX
3UC
-4AD (4-channel Analog Input)
5.4.4
BFM #10 to #13: Channel data
Numeric data type: Decimal (K)
Use these buffer memories to store the A/D converted digital values.
The channel data (BFM #10 to #13 for channels 1 to 4) and the data update timing will depend on the set
averaging time (BFM #2 to #5 for channels 1 to 4) or the digital filter setting condition (BFM #6 to #9 for
channels 1 to 4) as shown in the following table.
→ For a detailed description of the averaging time, refer to Subsection 5.4.2.
→ For a detailed description of digital filter functions, refer to Subsection 5.4.3.
*1.
"500
μs" represents the A/D conversion time.
However, if one of the channels uses the digital filter function, the A/D conversion time will be 5 ms for
all the channels.
Averaging 
time
(BFM #2 to #5)
Digital filter 
function
(BFM #6 to #9)
Channel data (BFM #10 to #13) update timing
Channel data type
Update timing
0 or less
0 (The digital filter 
will not be used.)
Immediate data
"0" will be set, and the 
averaging time setting error 
(b10 of BFM #29) will occur.
Each time the A/D conversion is performed, the 
data will be updated.
The update timing will be as follows:
Update time = 500
μs
*1 
× Number of 
selected channels
1
0 (The digital filter 
will not be used.)
Immediate data
1 to 1600
(The digital filter 
will be used.)
Immediate data
The digital filter function will 
be used.
Each time the A/D conversion is performed, the 
data will be updated.
The update timing will be as follows:
Update time = 5ms 
× Number of selected 
channels
2 to 400
0 (The digital filter 
will not be used.)
Average data
Each time the A/D conversion is performed, the 
data will be updated.
The update timing will be as follows:
Update time = 500
μs
*1
× Number of 
selected channels
401 to 4095
Average data
Each time the A/D conversion is performed for 
the set averaging time, the data will be updated. 
The update timing will be as follows:
Update time = 500
μs
*1
 × Number of 
selected channels 
× Averaging time
4096 or more
Average data
"4096" will be set, and the 
averaging time setting error 
(b10 of BFM #29) will occur.