P4088¶

Code: P4088
Message: EXTENDS names a type that is not a declared function block

This error occurs when a function block type names a base in EXTENDS that is not a declared function block: the name is not declared at all, or it names another kind of type, such as a structure or an interface.

Only a function block can be extended. To provide the methods an interface declares, use IMPLEMENTS.

Extending a standard function block, such as TON, is not supported yet and is reported as P9999.

Example¶

The following code will generate error P4088:

FUNCTION_BLOCK FB_Motor EXTENDS FB_Drive  (* Error: FB_Drive is not declared *)
END_FUNCTION_BLOCK

To fix this error, declare the base function block, or name one that is declared:

FUNCTION_BLOCK FB_Drive
END_FUNCTION_BLOCK

FUNCTION_BLOCK FB_Motor EXTENDS FB_Drive
END_FUNCTION_BLOCK

See Also¶

EXTENDS — EXTENDS
IMPLEMENTS — IMPLEMENTS
P4070 — IMPLEMENTS names a type that is not a declared interface

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