SWI_2PH: On/off switch with adjustable switch-on point and hysteresis
The SWI_2PH (FB432) block generates a binary output signal after a comparison between the input signal and the switch-on and switch-off point, the switch-on point shift and the hysteresis.
Functionality
The following functions are integrated in the block:
- Function can be enabled/disabled.
- Selectable direction of control action.
- Adjustable switch-on point shift.
- Adjustable hysteresis.
The block generates the binary output signal after a comparison between the input signal [In] and the effective switching points [EfOnPt] and [EfOffPt] that are defined by the switch-on point [SwiOnPt] (setpoint), hysteresis [Hys], and the switching point shift [ShftOnPt].
The hysteresis [Hys] defines the switching differential between the effective switching points [EfOnPt] and [EfOffPt].
The hysteresis [Hys] is kept by the variable [ShftOnPt] by parallel shifting of the effective switching points [EfOnPt] and [EfOffPt] relative to the switch-on point [SwiOnPt].
The effective switch-on point [EfOnPt] is defined by the switch-on point [SwiOnPt] (setpoint) and the switch-on point shift [ShftOnPt].
The effective switch-off point [EfOffPt] is given by the hysteresis [Hys] relative to the effective switch-on point [EfOnPt].
The block function can be fully enabled/disabled via pin [EnFnct].
The direction of control action is defined by [Actg].
Action: Direct ([Actg] = 0)
IF | THEN |
In > SwiOnPt + ShftOnPt | Out = 1 |
SwiOnPt + ShftOnPt - Hys < In < SwiOnPt + ShftOnPt | No action |
In < SwiOnPt + ShftOnPt - Hys | Out = 0 |
Action: Reverse ([Actg] = 1)
IF | THEN |
In < SwiOnPt + ShftOnPt | Out = 1 |
SwiOnPt + ShftOnPt < In < SwiOnPt + ShftOnPt + Hys | No action |
In > SwiOnPt + ShftOnPt + Hys | Out = 0 |
Inputs
Pin | E | Description | |
EnFnct | p | Enable function. | |
1 (Yes): The function is enabled. | |||
0 (No): The function is disabled. | |||
In | pa | Input. | |
SwiOnPt | pa | Switch-on point. | |
Hys | pa | Hysteresis. The hysteresis defines the switch-off point and the switching frequency. The greater the hysteresis, the lower the switching frequency. | |
ShftOnPt | pa | Shift of switch-on point. Offset for controlling the switch-on point. | |
Actg | pa | Control action. | |
0 (Direct ) | Switch-on at increasing input signal. | ||
1 (Reverse ) | Switch-on at decreasing input signal. | ||
Outputs
Pin | E | Description |
Out | a | Output. |
EfOnPt | a | Effective on-point. Calculated, effective switch-on point. |
EfOffPt | a | Effective off-point. Calculated, effective switch-off point. |
Input values
Pin | Description | Data type | Default value | E.g. Engineering unit or Text group | Min. | Max. |
EnFnct | Enable function. | Boolean | 1 (Yes) | No, Yes |
|
|
In | Input. | Real | 0.0 |
| -3.403E38 | 3.403E38 |
SwiOnPt | Switch-on point. | Real | 0.0 |
| -3.403E38 | 3.403E38 |
Hys | Hysteresis. | Real | 1.0 |
| 0.0 | 3.403E38 |
ShftOnPt | Shift of switch-on point. | Real | 0.0 |
| -3.403E38 | 3.403E38 |
Actg | Control action. | Boolean | 1 (Reverse ) | Direct, Reverse |
|
|
Output values
Pin | Description | Data type | Default value | E.g. Engineering unit or Text group | Min. | Max. |
Out | Output. | Boolean | 0 (Off) | Off, On |
|
|
EfOnPt | Effective on-point. | Real | 0.0 |
| -3.403E38 | 3.403E38 |
EfOffPt | Effective off-point. | Real | 0.0 |
| -3.403E38 | 3.403E38 |
Application
- In air conditioning and heating to control (disable and enable) components and aggregates.
- General: Performance of switching functions depends on a specific signal value.
Process response
The block is processed with the values at the inputs, starting from the first cycle in the process. During start-up, if the value [In] is between the effective switch-on and the effective switch-off point, the output is set to [Out] = 0 (Off).
Troubleshooting
Standard (see General rules and information).