FB_BA_Anlg3Pnt
![FB_BA_Anlg3Pnt 1:](Images/gif/9273238411__Web.gif)
The function block FB_BA_Anlg3Pnt is intended for control of three-point actuators for valves or dampers. A continuous control signal for positioning an actuator is converted into the binary commands for opening and closing.
If the deviation between the position setpoint fIn and the calculated actual position value fPos of the actuator is greater than the set threshold fHys / 2, the function block starts to correct the position by switching the outputs bOpn or bCls, depending on the amount of the control deviation:
| bOpn | bCls |
fIn - fPos > fHys / 2 | TRUE | FALSE |
fIn - fPos < - fHys / 2 | FALSE | TRUE |
If the function block reaches an end position fOut = 0 or fOut = 100 through a corresponding input value fIn, the corresponding switching output remains permanently set in order to safely reach this end position at the valve or damper:
| bOpn | bCls |
fOut = 0 | FALSE | permanently TRUE |
fOut = 100 | permanently TRUE | FALSE |
Any deactivation of the continuous signal must be implemented by the user through external programming.
The input fIn is automatically limited internally to the range of 0...100 %.
This also applies to the inputs fHys and fRefVal. The travel times nTiCls as well as nTiOpn are both limited downwards to 10 (milliseconds).
A rising edge at bRef triggers a referencing command (setting the calculated actual position to fRefVal).
If the drive has limit switches, these can also be detected directly by means of a digital input and used for referencing at bRef.
Inputs
VAR_INPUT
fIn : REAL;
fHys : REAL;
nTiCls : UDINT;
nTiOpn : UDINT;
bRef : BOOL;
fRefVal : REAL;
bCloseInit : BOOL;
END_VAR
Name | Type | Description |
---|---|---|
fIn | REAL | Setpoint for the actuator position [0…100 %]. Internally limited to values between 0 and 100. |
fHys | REAL | Hysteresis for the actuator position [0…100 %]. Internally limited to values between 0 and 100. |
nTiCls | UDINT | Run time of the actuator from open to closed [ms]. Internally limited to values between 0 and 100. |
nTiOpn | UDINT | Run time of the actuator from closed to open [ms]. Internally limited to values between 0 and 100. |
bRef | BOOL | Edge references the internal position memory of the drive to value of fRefVal [0…100 %]. |
fRefVal | REAL | Value for referencing the actuator with bRef [0…100 %]. Internally limited to values between 0 and 100. |
bCloseInit | BOOL | If this input is TRUE, output bCls is TRUE for the time udiTiOpn_ms. |
Outputs
VAR_OUTPUT
bCls : BOOL;
bOpn : BOOL;
fPos : REAL;
END_VAR
Name | Type | Description |
---|---|---|
bCls | BOOL | Output for closing the actuator. |
bOpn | BOOL | Output for opening the actuator. |
fPos | REAL | Current calculated actuator position [0…100 %]. |
Requirements
Development environment | Required PLC library |
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TwinCAT from v3.1.4024.22 | Tc3_BA2 from v5.2.5.0 |