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Multi-Input/Output Device
Parameterization and Operation
Valve Position Extended
In the intermediate position of the valve, the information on the valve position is extended with
the information "opening" and "closing". This information is determined by the current control
process and need not coincide with the actual direction of travel (e. g., when changing the set
position while the valve is in the intermediate position).
Numerical Value
1
2
3
4
0
The options "Valve Position" and "Valve Position Extended", and the setting "Use sensor values
for PV_D" in the Sensor Usage parameter are intricate to be used with the function block.
The transducer block transfers the valve position to the function block as part of the
READBACK_D parameter. From there, the valve position information is transferred to the
Primary Value parameter which can be cyclically transferred to a control system via
BKCAL_OUT_D. Alternatively, the valve position information can be used in a function block
application.
If an inversion is active in the function block, the numerical value "0" becomes "1" and all
numerical values 0 become "0". That means, all valid valve positions are inverted to "0".
Also, the IO options of the DO function block "SP-PV Track in LO" and "SP-PV Track in Man" do
no longer work because the range of values of the Primary Value parameter does not
correspond to that of SP_D.
In order to ensure a more straightforward use of the valve position information in the function
block, you can choose one of the following options.
These options show the valve position at the value range of the set position "closed" (0) or
"open" (1) and determine the position information to be issued in the intermediate position:
Intermediate => Closed: The intermediate position is always interpreted as "closed"
■
Intermediate => Open: The intermediate position is always interpreted as "open"
■
Intermediate => Next: During a closing process, the intermediate position is always
■
interpreted as "closed" and during an opening process as "open"
Intermediate => Last (default setting): During a closing process, the intermediate
■
position is interpreted as "open" and during an opening process as "closed"
The default setting "Intermediate => Last" has the effect that during an opening or closing
process, the last position is displayed until the valve has actually reached the reference
position. This is useful, e. g., for a sequential valve control when any further steps can only take
place after the valve has fully reached the desired position. In this case, only the reference
value must be compared with the feedback.
4.5.4
Target Mode
The "Target mode" determines the mode of operation of the MIO device. The modes of
operation are possible:
Out of service (OOS, default setting)
■
Auto
■
Manual (Man)
■
Valve Position
Closed
Open
Intermediate position/opening
Intermediate position/closing
Unkown
35
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