# MCV_DiscardParamChg

Discard changes

With this function block, the work list can be deleted, thus discarding all parameter changes in the work list.

## Notice

If the work list has already been activated with the MCV_ActivateParamChg function block, these changes are active in the controller and can no longer be reversed with this function block. If these modified parameter values are also to be reversed, the original list must be read in with the MCV_ChgParamSet function block.

Blockdiagramm

Parameters of the FB

VAR_IN_OUT
Variable name | Data type | Description
axis | AXIS_REF | Axis reference

VAR_INPUT
Variable name | Data type | Description
Execute | BOOL | A change is discarded on the rising edge.
NCListTypeIn | STRING | Identifier for parameter or list type e.g. "ACHS_MDS"
NCParamSetIDIn | UINT | Number of parameter set for which the changes are to be discarded.

VAR_OUTPUT
Variable name | Data type | Description
Valid | BOOL | Is TRUE when the parameter set changes were discarded successfully.
Busy | BOOL | Is TRUE when the FB is still active.
NCListTypeOut | STRING | Identifier for parameter or list type e.g. "ACHS_MDS"
NCParamSetIDOut | UINT | Number of parameter set for which the changes are to be discarded.
NCWarning | BOOL | Is TRUE if a warning occurs in the ISG-MCP.
NCError | BOOL | Is TRUE when an error occurs in the MCE when changes are discarded.
NCErrorCode | UDINT | Error code of the error or warning occurring in the ISG-MCP.
Error | BOOL | Is TRUE if the FB is in error state. The parameter set changes were not discarded successfully.
ErrorID | WORD | Error code.

1) Availability is dependent on the MCE used.

Behaviour of the FB

- The FB is in an error state if "error" = TRUE. The parameter changes could not be reversed correctly. An error has occurred either in the function block itself or in the ISG-MCP. The "NCError" output parameter indicates whether an error has occurred in the ISG-MCP.

A frequent cause of ISG-MCP errors are absent write privileges or a write-protected work list because, in these cases, the work list cannot be deleted.