[SWI_2PH] On/off switch with adjustable switch-on point and hysteresis

Function block SWI_2PH generates a binary output signal based on a comparison of the input signal and the switch-on and switch-off point, the switch-on point shift and the hysteresis.

SWI_2PH generates a binary output signal based on a comparison of the input signal and the switch-on and switch-off point, the switch-on point shift and the hysteresis.

Functioning

SWI_2PH generates the binary output signal based on a comparison of the input signal [In] and the effective switching points [EffOnPt] and [EffOffPt] defined by the switch-on point [SwiOnPt], hysteresis [Hys], and the switch-on point shift [ShSwiOn].

The hysteresis [Hys] defines the switching difference between the effective switching points [EfOnPt] and [EfOffPt].

Switch-on point shift [ShftOnPt] allows for maintaining hysteresis [Hys] by shifting in parallel 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] 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].

Enabling and disabling the function

The function can be enabled/disabled via [EnFnct].

Integrated functions

  • Enabling and disabling the function
  • Selectable direction of control action
  • Adjustable switch-on point shift
  • Adjustable hysteresis

Direction of control action

The direction of control action is defined by [Actg].

Direct acting ([Actg] = 0)

  • If the value at input [In] is greater than the sum of [SwiOnPt] and [ShftOnPt], value 1 is issued at output [Out].
  • If the sum of [SwiOnPt] and [ShftOnPt] minus [Hys] is less than the sum of [SwiOnPt] and [ShftOnPt], no change occurs.
  • If the value at input [In] is greater than the sum of [SwiOnPt] and [ShftOnPt] minus [Hys], value 0 is issued at output [Out].

Reverse acting ([Actg] = 1)

  • If the value at input [In] is smaller than the sum of [SwiOnPt] and [ShftOnPt], value 1 is issued at output [Out].
  • If the value at input [In] is greater than the sum of [SwiOnPt] and [ShftOnPt] and smaller than the sum of [SwiOnPt], [ShftOnPt], and [Hys], no change occurs.
  • If the value at input [In] is greater than the sum of [SwiOnPt], [ShftOnPt], and [Hys], value 0 is issued at output [Out].
Pins

Input

Description

Data type

Default value
Value range

EnFnct

Enable function

Enables the function.

Boolean

1

0 - The function is disabled.
1 - The function is enabled.

In

Input

Real

0.0

SwiOnPt

Switch-on point

Real

0.0

Hys

Hysteresis

Real

1.0

ShftOnPt

Shift of switch-on point

Real

0.0

Actg

Control action

Determines the relationship between manipulated and control variable.

Boolean

1

0 - Direct effect, such as cooling or dehumidification.
1 - Indirect effect, such as heating or humidification.

 

Output

Description

Data type

Default value
Value range

Out

Output

Boolean

0

EfOnPt

Effective on-point

Real

0.0

EfOffPt

Effective off-point

Real

0.0

Application
  • Heating and cooling control to disable (add or remove) components.
  • General: Execution of switching functions depends on a specific signal value.
Process response

SWI_2PH is processed starting with the first process cycle using the values pending at the inputs. If value [In] is between the effective switch-on and switch-off point during start-up, the output [Out] is set to 0.