Rules for the validation of an application

IEC 61131-3 portability rule

C-blocks must only be contained in libraries.
This model rule checks whether the used →C-blocks are contained in libraries. Other C-blocks are reported.

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IEC 61131-3 design rule

The usage of expressions in value fields is restricted to literals, constants or variables.
This model rule checks the usage of →expressions in →value fields . Only →literals, →constants or →variables can be used, other expressions are reported.

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ERROR (def),
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FBD

IEC 61131-3 design rule

The usage of blocks is restricted either completely or only for defined types.
This model rule is configurable to restrict the use of →blocks or their allowed types.

Restriction: Currently the blocks and their allowed types cannot be defined in the graphical user interface but only in the file configuring the model rule. Without a modified file configuring the model rule, it does not make sense to apply this rule at the moment.

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ERROR (def),
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IEC 61131-3 design rule

Direct lines across pages must not be used.
This model rule checks whether there are direct lines across the pages. Such lines are reported.

See under " Automatic routing of lines " for information when logi.CAD 3 creates such direct lines.

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ERROR, INFO,
WARNING (def)

FAST,
NORMAL (def),
EXPENSIVE

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FBD

IEC 61131-3 design rule

Direct lines on the same page must not be used.
This model rule checks whether there are direct lines on the same page. Such lines are reported.

If you change the preset type from EXPENSIVE to NORMAL or FAST , it is possible that the memory consumption increases when importing projects with FBD-objects or opening FBD-objects respectively. Likewise, there might be delays when scrolling within an FBD-object.

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ERROR, INFO,
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FAST,
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not relevant

FBD

IEC 61131-3 design rule

Inputs must be positioned on the left block edge, outputs on the right one.
This model rule checks on which block edge the inputs/outputs are positioned. The rule reports inputs not positioned on the left block edge and outputs not positioned on the right block edge.

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ERROR,
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ST, FBD

IEC 61131-3 design rule

Inputs and outputs must not be negated.
This model rule checks for negated in-/outputs and reports them.

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ERROR,
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FAST (def),
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FBD

IEC 61131-3 design rule

Elements in an interface of function blocks and functions must not overlap.
This model rule checks whether elements in the interface of →function block and →functions overlap.

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ERROR (def),
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FBD

IEC 61131-3 design rule

Connectors or continuations must not be used.
This model rule checks if →connectors or →continuations are used.

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ERROR (def),
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FBD

IEC 61131-3 design rule

Instances of function blocks must not be called multiple times.
This model rule checks whether→instances of function blocks are called →called multiple times.

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IEC 61131-3 design rule

Each program must be assigned to a task.
This model rule checks whether each program type is assigned to a task. Other program types are reported.

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IEC 61131-3 design rule

Negations of unconnected block inputs are not allowed.
This model rule checks whether there are negations of block inputs, if these inputs are not connected. Such block inputs are reported.

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ERROR,
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FAST (def),
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FBD

IEC 61131-3 design rule

A connector must be connected to a source.
This model rule checks whether a →connector is connected to a source. If not, the connector is reported.

This rule is also applied to a block input that is connected with a connector without a source. When the rule is activated, such constructs are reported with the message Expression has no return value while other connectors without a source are reported with the message Connector name is not connected to any source. This is in conflict with a rule . When the rule is deactivated, both messages are not reported.

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FBD

IEC 61131-3 design rule

Only identifiers conform to predefined specifications must be used for projects/folders/objects.
This model rule checks whether the names of projects/folders/objects are conform to predefined specifications. See "Predefined specifications for names of projects/folders/objects" for more information on these specifications.

An identifier of an object or a project is already checked when the object/project is created in the project explorer. Subsequently, the name entered in the dialog must be conform to the predefined specifications.
Identifiers of folders are only checked, when the command to start the validation is selected.

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ERROR,
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EXPENSIVE

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IEC 61131-3 design rule

Lines leading from right to left must not be used.
This model rule checks whether lines leading from right to left are used. Such lines are reported.
Note: Connections via →connectors and →continuations are not checked by this rule.

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ERROR, INFO,
WARNING (def)

FAST,
NORMAL (def),
EXPENSIVE

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FBD

IEC 61131-3 design rule

Namespaces of language elements must match the identifier of the parent namespace folder.
This model rule checks whether the →namespaces of all language elements match the identifier of the parent namespace folder. Deviations are reported. If there is no namespace folder for the language elements, no deviations are reported.

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IEC 61131-3 design rule

Namespace folders need a unique identifier.
This model rule checks whether there are two or more namespace folders with the same identifier. Deviations are reported.

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IEC 61131-3 design rule

ST-objects must not contain more than one element on the top level.
This model rule checks whether ST-objects contain more than one element on the top level of the ST-object. Such ST-objects are reported.

Such elements are e.g. →POUs, →data types or →interfaces.

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IEC 61131-3 design rule

ST-objects may only contain elements with the name of the ST-object on the top level.
This model rule checks whether the name of elements (declared on the top level within an ST-object) is matching the name of this ST-object. Elements with other names are reported.

Such elements are e.g. →POUs or →interfaces. Please observe: This rule is not applied for user-defined →data types in ST-objects.

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IEC 61131-3 design rule

Illegal elementary data types must not be used.
This model rule checks whether illegal →data types are used. The usages of such data types are reported as illegal.

Best practice how to get information which data types are illegal: Select this rule in the property page Validation or in the dialog Configure Validation for resource and check the content of the field Details.

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ERROR,
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FAST, NORMAL (def),
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IEC 61131-3 usage rule

Number of resources per platform is limited.
This model rule checks if the maximum number of →resources is exceeded for a platform.

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–

IEC 61131-3 usage rule

References to local variables must not be used in functions/methods.
This model rule checks whether references to local variables are used in functions/methods. Such references to local variables are reported.

If you deactivate the rule , logi.CAD 3 deviates from the →IEC-standard. As a consequence of the deactivation, this enhancement is valid for logi.CAD 3:
→References to local, temporary →variables can be used in →functions / →methods .

Here, "local, temporary variables" identifies the variables for which a temporary memory is assigned while the function/methods is executed. Hence, the following variables are affected:

• →internal variables (= VAR ... END_VAR)

• →input variables (= VAR_INPUT ... END_VAR)

• →output variables (= VAR_OUTPUT ... END_VAR)

• →in-out variables (= VAR_IN_OUT ... END_VAR)

• →temporary variables (= VAR_TEMP ... END_VAR) – However due to restrictions, the v ariables declared in VAR_TEMP ... END_VAR are not allowed as argument of REF(...) anyway (see "Declaration of reference variables (incl. assignments to them)" for details).

Moreover, observe that it is possible to implement constructs leading to invalid memory accesses. Such constructs are not detected by logi.CAD 3 . Hence, avoid appropriate constructs. See "Example for a problematic access".

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ST, FBD

IEC 61131-3 usage rule

An output of a function block must not be assigned to a VAR_IN_OUT variable
This model rule checks whether there are assignments from an output of a →function block to a VAR_IN_OUT variable. Such assignments are reported.

If you deactivate the rule , logi.CAD 3 deviates from the →IEC-standard. As a consequence of the deactivation, this enhancement is valid for logi.CAD 3 (for FBD): →Assignments from an output of a →function block to a VAR_IN_OUT variable (= →in-out variable) are allowed.

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IEC 61131-3 usage rule

Assignments to output variables of a function block are not allowed outside of function blocks.
This model rule checks whether there are →assignments to output variables (= VAR_OUTPUT) of a function block outside of function blocks. Such assignments are reported.

If you deactivate the rule , logi.CAD 3 deviates from the →IEC-standard. As a consequence of the deactivation, this enhancement is valid for logi.CAD 3: →Output variables (= VAR_OUTPUT) of →function block instances can be written to outside of the function block.

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ERROR (def),
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ST, FBD

IEC 61131-3 usage rule

Assignments to input variables within the POUs are not allowed.
This model rule checks whether there are →assignments to →input variables within →function blocks. Such assignments are reported. Exceptions are assignments to →reference variables within function blocks because they are always allowed.
Assignments to input variables within →functions are never allowed in general. Again, exceptions are assignments to reference variables because they are always allowed in functions as well.

If you deactivate the rule , logi.CAD 3 deviates from the →IEC-standard. As a consequence of the deactivation, this enhancement is valid for logi.CAD 3 (FBD): →Input variables can be written to inside of →function blocks.

In logi.CAD 3, assignments to input variables of →programs are not possible at all. Hence, this rule is neither applied to such assignments .

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ERROR (def),
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FAST (def),
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element

ST, FBD