MC_OverrideFilter

MC_OverrideFilter 1:

The function block MC_OverrideFilter can be used to convert an unfiltered override value consisting of digits (e.g. a voltage value of an analog input terminal) into a filtered override value that matches the cyclic axis interface (PlcToNc) (DWORD in the range 0...1000000). This filtered override is also available in percent (LREAL in the range 0...100%).

The raw input value is limited to a validity range by "LowerOverrideThreshold" and "UpperOverrideThreshold", and implemented as parameterizable steps (resolution) ("OverrideSteps"). After each override change at the output of the FB, the system internally waits for a minimum recovery time ("OverrideRecoveryTime") before a new override value can be applied. The only exceptions are the override values 0% and 100%, which are always implemented without delay for safety reasons.

MC_OverrideFilter 2:

Due to the gradation of the output override value ("OverrideValueFiltered"), the filtered override can become zero with very small override input values ("OverrideValueRaw"). A zero override leads to standstill of the axis. If total standstill is undesired, "OverrideValueRaw" should not fall below the smallest level.

MC_OverrideFilter 3: Inputs 

VAR_INPUT
    OverrideValueRaw       : DINT;
    LowerOverrideThreshold : DINT := 0; (* 0...32767 digits *)
    UpperOverrideThreshold : DINT := 32767; (* 0...32767 digits *)
    OverrideSteps          : UDINT := 200; (* 200 steps => 0.5 percent *)
    OverrideRecoveryTime   : TIME := T#150ms; (* 150 ms *)
END_VAR

Name

Type

Description

OverrideValueRaw

DINT

Raw, unfiltered override value (e.g. a voltage value of an analog input terminal).

LowerOverrideThreshold

DINT

Lower threshold that limits the raw override value.

UpperOverrideThreshold

DINT

Upper threshold that limits the raw override value.

OverrideSteps

UDINT

The specified steps (override resolution).

OverrideRecoveryTime

TIME

Minimum recovery time, after which a new filtered override value is applied to the output. However, the override values 0% and 100% are implemented without delay.

MC_OverrideFilter 4: Outputs

VAR_OUTPUT
    OverrideValueFiltered   : DWORD; (* 0...1000000 counts *)
    OverridePercentFiltered : LREAL; (* 0...100 % *)
    Error                   : BOOL;
    ErrorId                 : UDINT;
END_VAR

Name

Type

Description

OverrideValueFiltered

DWORD

The filtered override value in digits (the data type matches the override in the cyclic axis interface 0..1000000).

OverridePercentFiltered

LREAL

Filtered override value in percent (0..100%).

Error

BOOL

TRUE, if an error occurs.

ErrorID

UDINT

If the error output is set, this parameter supplies the error number.

Possible error number

Possible causes

MC_ERROR_PARAMETER_NOT_CORRECT

  • OverrideSteps <= 1
  • LowerOverrideThreshold >=
    UpperOverrideThreshold

Requirements

Development environment

Target system type

PLC libraries to include

TwinCAT v3.0.0

PC or CX (x86 or x64)

Tc2_MC2