FB_BA_Anlg3Pnt

The function block is intended for control of three-point actuators for valves or dampers.

A continuous control signal for positioning an actuator is converted into binary commands for opening and closing.

If the deviation between the set position value rIn and the calculated actual position value rPos of the actuator exceeds the set threshold value rHys/2, the function block starts to correct the position by switching the outputs bOpn or bCls, depending on the magnitude of the control deviation:

If the function block reaches an end position rOut=0 or rOut=100 through a corresponding input value rIn, the corresponding switching output remains permanently set in order to safely reach this end position at the valve or damper:

Any deactivation of the continuous signal must be implemented by the user through external programming.

The input rIn is automatically limited to the range 0..100% internally.

This also applies to the entries rHys and rRefVal. The travel times udiTiCls_ms and udiTiOpn_ms both have a lower limit value of 10 (milliseconds).

A rising edge at bRef triggers a referencing command (the calculated actual position is set to rRefVal).

If the drive has limit switches, they can be sampled directly via the digital input and used for referencing at bRef.

VAR_INPUT

rIn         : REAL;
rHys        : REAL;
udiTiCls_ms : UDINT;
udiTiOpn_ms : UDINT;
bRef        : BOOL;
rRefVal     : REAL;
bCloseInit  : BOOL;

rIn: Setpoint for the actuator position [0 - 100%]. Internally limited to values between 0 and 100.

rHys: Hysteresis for the actuator position [0 - 100%]. Internally limited to values between 0 and 100.

udiTiCls_ms: Run time of the actuator from open to closed [ms]. Internally limited to values between 0 and 100.

udiTiOpn_ms: Run time of the actuator from closed to open [ms]. Internally limited to values between 0 and 100.

bRef: Edge references the internal position memory of the drive to value of rRefVal [0 - 100%].

rRefVal: Value for referencing the actuator with bRef [0 - 100%]. Internally limited to values between 0 and 100.

bCloseInit: If this input is TRUE, output bCls is TRUE for the time udiTiOpn_ms

VAR_OUTPUT

bCls    : BOOL;
bOpn    : BOOL;
rPos    : REAL;

bCls: Output for closing the actuator.

bOpn: Output for opening the actuator.

rPos: Current calculated actuator position [0 - 100%].

Requirements