800xA 5.1 RevC SDInReal function block
I faced with strange behavior of this Function block. When "Filter Time" parameter is set, differ from the "0" Out Value is setting "0" after Warm Controller restart and begin grow to real value, that's why LL Alarm is Activate.
Is it normal?
I try to do it on Soft Controller and PM865, the same situation.
However, why is the alarm being triggered ? If the input value doesn't change during the warm start then an alarm condition caused by poor filtering should still be very rare.
- Ensure your input value is "Retain" during the warm start and not being reset to zero
- For a real Signal Input, filter times of more than 1 to 2 seconds are HIGHLY suspicious. Input signals should not change that much. Do not use signal filtering to hide real process problems like incorrectly installed instrumentation.
The SDRealIn function block in my 5.1 RevD system handles filtering correctly during a warm start. There is no bump transition of the "Out" value and the filter continues normally. Screen shot is taken immediately after a warm start of the module.