Bfm#27: Abrupt Change Detection Status - Mitsubishi Electric FX3G User Manual

FX /FX /FX /FX /FX
3S 3G 3GC 3U
FX -4AD/FX -4AD (4-channel Analog Input)
3U 3UC

5.4.10 BFM#27: Abrupt change detection status

When channel data (BFM#10 to #13) is updated, if the difference between the previous value and the new
value is larger than the set abrupt change detection value (value set in BFM#91 to #94), the following
operation will be performed:
• If "(new value) - (previous value) > (abrupt change detection value)":
The "+" direction bit will turn on.
• If "(previous value) - (new value) > (abrupt change detection value)":
The "-" direction bit will turn on.
1. Assignment of each bit of BFM#27
For the abrupt change detection function of each channel, the "+" and "-" directions are assigned as shown in
the following table:
Bit No.
b0
b1
b2
b3
b4
b5
b6
b7
b8 to b15
2. Caution regarding use of abrupt change detection status data
• To use the abrupt change status data, be sure to turn on the abrupt change detection function (b2 of
BFM#22).
• Perform one of the following operations to turn off the previously turned on bit:
- Turn the power off and on.
- Turn on b2 of BFM#99 to reset the abrupt change detection error status.
- Write "H0000" in BFM#27 as the abrupt change detection status data.
• Even if abrupt change is detected, channel data (BFM#10 to #13) will be continuously updated.
• The abrupt change detection status data automatic transfer function is not supported when connected and
used with the FX5U or FX5UC CPU module.
3. Abrupt change detection status data automatic transfer function (b6 of BFM#22)
If the abrupt change detection status data automatic transfer-to data register is specified in BFM#127, the
data in BFM#27 can be transferred to the specified data register.
When abrupt change is detected, data will be automatically transferred from the 4AD to the PLC. For this
reason, the PLC does not need any program for reading the data, and the scan time of the PLC can be
shortened.
Convenient function
setting
ON = Valid
BFM#22 b2:ON
BFM#22 b6:ON
B-34
PLC User's Manual - Analog Control Edition
3UC
→ For a detailed description of abrupt change detection status data resetting,
Channel number
"-" direction for abrupt change detection
ch1
"+" direction for abrupt change detection
"-" direction for abrupt change detection
ch2
"+" direction for abrupt change detection
"-" direction for abrupt change detection
ch3
"+" direction for abrupt change detection
"-" direction for abrupt change detection
ch4
"+" direction for abrupt change detection
Transfer-from memory
BFM#27
Description
Not used.
Automatic data transfer function
→
5 Buffer Memory (BFM)
5.4 Buffer Memory Details
Initial value: H0000
Numeric data type: Hexadecimal (H)
refer to Subsection 5.4.18.
 : Represents a numeric value.
Transfer-to data register specification
(BFM#127: K 
D 
)