Treatment For Sudden Change Of Temperature Conversion Data - Hitachi HIDIC EH-150 Instruction Manual

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 the difference between the latest data and the
previous data is 5 degrees or more, the latest data is ignored as abnormal data.
Note: Please change each value for your system.
Example of program
1)
DR000 == DX000
DR002 == DX002
R7E3
2)
DR008 == DR000
DR00A == DR002
3)
WR0008 == WR0008 - WR0000
ABS (WR0008 , WR0008)
WR0009 == WR0009 - WR0001
ABS (WR0009 , WR0009)
WR000A == WR000A - WR0002
ABS (WR000A , WR000A)
WR000B == WR000B - WR0003
ABS (WR000B , WR000B)
4)
WR0008
<
WR0010 == WR0000
H00CC
WR0009
<
WR0011 == WR0001
H00CC
WR000A
<
WR0012 == WR0002
H00CC
WR000B
<
WR0013 == WR0003
H00CC
5)
DR0008 == DR0010
DR000A == DR0012
This sample program does not output any signal for the abnormal data. Please make additional
depending on the situation.
8. Error Detection Processing
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 latest data and the
previous data is 5 degrees or more, the data will be
stored in WR10 to WR13 as normal values.
Updates the previous data.
The abnormal data will be invalid.
8-2
circuits