Mitsubishi Electronics MELSEC-F Manuel D’Utilisation
B-28
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)
5.4.2
BFM #2 to #5: Averaging time
Setting range: 1 to 4095
Initial value: K1
Numeric data type: Decimal (K)
To change the channel data type from the immediate data (channels 1 to 4: BFM #10 to #13) to the average
data, set the desired averaging time (channels 1 to 4 : BFM #2 to 5).
The relation between the set averaging time and the corresponding operation is shown in the following table.
data, set the desired averaging time (channels 1 to 4 : BFM #2 to 5).
The relation between the set averaging time and the corresponding operation is shown in the following table.
→ For a detailed description of channel data update timing, refer to Subsection 5.4.4.
1. Application
If the measurement signal contains comparatively reduced ripple noise, such as supply voltage frequency,
averaging will result in obtaining of stable data.
averaging will result in obtaining of stable data.
2. Cautions regarding averaging time setting
• To use the averaging function, be sure to set the digital filter of the corresponding channel to "0". (Digital
filter setting: BFM #6 to #9 for channels 1 to 4)
To use the digital filter function, be sure to set the averaging time of the corresponding channel to "1".
(Averaging time: BFM #2 to #5 for channels 1 to 4)
If the averaging time is set to a value other than "1" and the digital filter (BFM #6 to #9 for channels 1 to 4)
is set to a value other than "0", the digital filter setting error (b11 of BFM #29) will occur.
To use the digital filter function, be sure to set the averaging time of the corresponding channel to "1".
(Averaging time: BFM #2 to #5 for channels 1 to 4)
If the averaging time is set to a value other than "1" and the digital filter (BFM #6 to #9 for channels 1 to 4)
is set to a value other than "0", the digital filter setting error (b11 of BFM #29) will occur.
• If one of the channels uses the digital filter, the A/D conversion time will be set to 5 ms for all the channels.
• If the averaging time is out of the setting range, the averaging time setting error (b10 of BFM #29) will
• If the averaging time is out of the setting range, the averaging time setting error (b10 of BFM #29) will
occur.
• If the averaging time is set, the data history function cannot be used.
Averaging
time (BFM
time (BFM
#2 to #5)
Channel data (BFM #10 to #13) type
Error descriptions
0 or less
Immediate data
(Each time the A/D conversion is performed, the channel
data will be updated.)
(Each time the A/D conversion is performed, the channel
data will be updated.)
K0 will be set, and the averaging time
setting error (b10 of BFM #29) will
occur.
setting error (b10 of BFM #29) will
occur.
1 (initial
value)
value)
Immediate data
(Each time the A/D conversion is performed, the channel
data will be updated.)
(Each time the A/D conversion is performed, the channel
data will be updated.)
-
2 to 400
Average data
(Each time the A/D conversion is performed, the average
value will be calculated and the channel data will be
updated.)
(Each time the A/D conversion is performed, the average
value will be calculated and the channel data will be
updated.)
-
401 to 4095
Average data
(Each time the A/D conversion data reaches the averaging
time, the average data will be calculated and the channel
data will be updated.)
(Each time the A/D conversion data reaches the averaging
time, the average data will be calculated and the channel
data will be updated.)
-
4096 or more
Average data
(Each time the A/D conversion is performed, the channel
data will be updated.)
(Each time the A/D conversion is performed, the channel
data will be updated.)
4096 will be set, and the averaging
time setting error (b10 of BFM #29) will
occur.
time setting error (b10 of BFM #29) will
occur.