Siemens SITRANS PCS 7 Function Manual page 272

SIPART PS2 PA
8.1 SipPS2PA
If the control valve travels in the direction of the "Close" position, the output FbkClsgOut = 1:
● FbkClsgOut is set when MV.Value < RbkOut.Value and PosReached.Value is not = 1.
Valve open ("Open")
When the control valve reaches the "Open" position, the output FbkOpenOut.Value = 1:
● With a binary limit switch for the "Open" position (NoFbkOpen = 0):
The valve is considered open when FbkOpenOut is set. FbkOpenOut is set when Rbk ≥
PosDiOpen and FbkOpen = 1.
● Without a binary limit switch for the "Open" position (NoFbkOpen = 1):
The valve is considered open when FbkOpenOut is set. FbkOpenOut is set when Rbk ≥
PosDiOpen.
Valve opens
If the control valve travels in the direction of the "Open" position, the output FbkOpngOut = 1:
● FbkOpngOut is set when MV.Value > RbkOut.Value and PosReached.Value is not = 1.
Valve has reached defined position
If the control valve is sent to a specified intermediate position (MV > PosDiClose and MV <
PosDiOpen), the targeted position is reached when the difference MV.Value - RbkOut.Value
is within the configured tolerance range ± PosDeadBand and thereby ER.Value = 0.0.
If the control valve is set to the end position "Open" (MV.Value >= PosDiOpen), this position
is reached when ER.Value = 0.0 and also FbkOpenOut.Value = 1.
If the control valve is set to the end position "Closed" (MV.Value <= PosDiClose), this position
is reached when ER.Value = 0.0 and also FbkCloseOut.Value = 1.
When the control valve reaches the specified position, the output PosReached = 1 is set.
Dynamic monitoring
The monitoring is based on the effective feedback signals FbkOpenOut and FbkCloseOut
and not directly on the feedback inputs FbkOpen and FbkClose.
The monitoring is only active if the control valve is within the control range. The operating range
is determined by the limits PosDiClose and PosDiOpen (PosDiClose < Rbk <
PosDiOpen).
When the control valve is within the control range, to reach one of the two end positions (MV ≥
PosDiOpen or MV ≤ PosDiClose), the targeted end position must be reached within the time
defined by MonTiDynamic.
If there are binary signals for the feedback of the control valve, the monitoring time for reaching
the configured values for the "Open" (PosDiOpen) or "Closed" (PosDiClose) position of the
manipulated variable is started (start MonTiDynamic if MV ≤ PosDiClose or MV ≥
PosDiOpen).
272
SITRANS Library for PCS 7
Function Manual, 05/2019, A5E35351976-11