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8. Error Detection Processing
8-2
8.2 Treatment for a Sudden Change of Temperature Conversion Data
When the temperature conversion data is changed suddenly due to the disconnection of external
wiring or influence of noise, the system judges it to be an abnormal condition.
In the example shown below, every scanned data is read in. If a change of 5ºC(Note) or more from the
previously read data is found, the condition is judged to be abnormal and data is aborted.
Note: Change each value to your system.
Example of program
1)
2)
3)
4)
5)
In the example of this program, no protective action or warning against abnormal data is performed.
Make additional circuits depending on the situation.
WR000B
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H00CC
WR0008
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H00CC
WR0009
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H00CC
Every scanned data is read in and
the data is stored in DR0 and DR2.
For only the initial scanned data,
put the read into the previous
data(DR8 to DRA).
The absolute value of the difference
between the previous data and read
data is calculated.
If the difference between the
previous data and read data is less
than 5ºC, put the read data into
WR10 to WR13. In the following
program, the values of WR10 to
WR13 are treaded a s normal value.
Updates the previous data.
When an error occurred, the data is
not updated and instead the previous
data is held.
WR0008 == WR0008 - WR0000
ABS (WR0008 , WR0008)
WR0009 == WR0009 - WR0001
ABS (WR0009 , WR0009)
WR000A == WR000A - WR0002
ABS (WR000A , WR000A)
WR000B == WR000B - WR0003
ABS (WR000B , WR000B)
DR0008 == DR0010
DR000A == DR0012
DR000 == DX000
DR002 == DX002
DR008 == DR000
DR00A == DR002
WR0010 == WR0000
WR0012 == WR0002
WR0011 == WR0001
WR0013 == WR0003
WR000A
<
H00CC