Signal input bad status and its effect on PIDCC blocks.
- How to generate a alarm of input signal bad from SignalRealM ( standard library).
- How to make PID change to manual when input goes bad. please let me know the standard pratices.
These all function avaialble as defualt in MOD300, but not in 800M?.
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Standard lib:SignalInRealM control module has the following fecility:
– SignalInRealM Control Module
1.The component ControlConnection.Forward.Status displays the Uncertain
status for underflow and overflow.
2.When there is an underflow or overflow of the input signal, the Warning and Error parameters are set to true.
please refer more the attached http://abblibrary.abb.com/global/scot/scot387.nsf/veritydisplay/f4f6a6cec33532a
If you want to generate any alarm/events then please follow the things.
1.For signals where supervision of Overflow and Underflow is critical, application code shall be created directly on the input signal to detect and react on status 16#55 (01010101) overflow , 16#56 (01010110) underflow and 16#40 (01000000) to generate the alarm & events
How to make PID change to manual when input goes bad: Regarding this PIDCC has the following feature like Setpoint backtracking:you have to select this in the "common"tab of extended faceplate with this you gain only when the PID is in manual mode then setpoint will track the PV this fecility is available in the PIDCC control module Please refer the snap attached.
If you want PIDCC control module should goes to manual mode when PV of the input signal goes bad that feature is not available directly in this PIDCC control module so you have can write a code by using the signal quality of the input singal like
signal quality Ok=signal#status and 16#C0 so when the signal deviates from this then put PIDCC Interactionparameter.faceplate.man=1 else 0
Whereas these features are readily available in MOD300 PID block.
hope this clarifies your doubt