Resolving Disabled Operator Level Authorization Attributes on CFC Block Pins in PCS 7

In SIMATIC PCS 7 Continuous Function Chart (CFC), the Operator Level Authorization field (Op_Level) on block I/O properties remains grayed out and disabled when attribute syntax violates case-sensitivity rules or when prerequisite WinCC compile tags are missing. Enabling the field requires assigning the exact case-sensitive attribute 'Op_Level' (not 'OP_Level') to the parameter, verifying that attribute 'S7_m_c = true' is assigned to the pin, and ensuring the enclosing block header also asserts 'S7_m_c = true'.

Role of Op_Level and S7_m_c Attributes in PCS 7 Engineering

SIMATIC PCS 7 integrates controller logic with the WinCC supervisory layer through technological system attributes declared in STEP 7 block interfaces (SCL or LAD/FBD):
* S7_m_c (Message and Control): Dictates whether a block instance or specific block I/O pin is transferred into WinCC Tag Management during AS-OS compilation.
* Op_Level (Operator Level Authorization): Specifies the required operator privilege level (e.g., Level 5 Process Controlling, Level 6 Higher Process Controlling) required to modify that parameter from WinCC faceplates.
* In CFC, double-clicking a block pin opens the Properties - Input/Output dialog, where engineers can customize the Operator Level Authorization. When this field is disabled (grayed out), the parameter cannot be assigned user-specific security rights.

The Strict Case-Sensitivity Rule: Op_Level vs. OP_Level

The CFC compiler and dialog parser adhere strictly to case-sensitive identifier evaluation for system attributes:
* Declaring the attribute as OP_Level, op_level, or OP_LEVEL is rejected by the internal parser. The compiler treats the entry as an arbitrary custom string rather than the recognized system attribute.
* The required exact case syntax is:
$$\mathbf{Op_Level}$$
* Correcting OP_Level to Op_Level immediately enables the Operator Level Authorization drop-down list in the CFC block pin properties dialog.

Prerequisite Attribute Chain: Pin S7_m_c and Block Header S7_m_c

Even with correct capitalization, Op_Level remains disabled if the parameter is not authorized for WinCC communication:
1. Block Header Requirement: The function block header must declare S7_m_c := 'true'. Without this, the entire block is excluded from WinCC data exchange.
2. Parameter Pin Requirement: The specific input or output pin must declare S7_m_c := 'true'. If the pin is internal to the AS, operator level security does not apply, and CFC grays out the field.
3. Both conditions must be satisfied concurrently:
scl FUNCTION_BLOCK FB_CustomControl { S7_m_c := 'true' } VAR_INPUT SP_Ext { S7_m_c := 'true'; Op_Level := '1' } : REAL; // Field Enabled InternalParam { S7_m_c := 'false' } : REAL; // Field Disabled END_VAR

Step-by-Step Procedure to Enable and Configure Operator Authorizations in SCL/CFC

To restore and configure operator authorization levels:
1. Open SCL Source File: In SIMATIC Manager, locate the SCL source file generating the function block.
2. Inspect Block Header: Verify that { S7_m_c := 'true' } appears immediately after the block declaration.
3. Inspect Pin Declaration: Locate the target parameter under VAR_INPUT or VAR_OUTPUT.
4. Apply Correct Syntax:
scl SetPoint { S7_m_c := 'true'; Op_Level := '1' } : REAL;
5. Compile SCL Source: Compile the source (File -> Compile). Confirm that compilation succeeds with 0 errors.
6. Update Master Data Library and Charts:
* In SIMATIC Manager, copy the updated FB to the Master Data Library.
* Execute Options -> Charts -> Update Block Types... across all project charts.
7. Verify in CFC: Open the chart, double-click the block pin: confirm that the Operator Level Authorization field is active and allows selecting authorization levels 1 through 10.

Verification

In CFC, open the block pin properties dialog: confirm that the Operator Level Authorization field is editable.
Select an authorization level (e.g., Level 6: Higher Process Controlling) and click OK.
Execute an AS-OS compilation (Changes Only).
In WinCC OS runtime, log in with an operator account possessing only Level 5 privileges: confirm that the parameter input field on the faceplate is locked/disabled.
Log in with a supervisor account possessing Level 6 privileges: confirm that the input field enables and accepts setpoint commands.

Limitations and Operational Precautions

Modifying block attributes in SCL changes the block interface signature; execute Update Block Types to prevent compilation mismatch errors.
Avoid assigning excessively high authorization levels to daily operating parameters; align security levels with your plant's standard operating procedures.
Attribute names inside curly braces { ... } must not contain unquoted spaces or invalid syntax.

Engineer FAQ

What causes the Operator Level Authorization field to be disabled in CFC?
Incorrect capitalization (e.g., OP_Level instead of Op_Level) or missing S7_m_c := 'true' attributes.
Is the Op_Level attribute case-sensitive?
Yes, the CFC parser requires exact camel-case capitalization: Op_Level.
Can Op_Level be configured if S7_m_c is set to false?
No, operator authorizations apply strictly to variables exposed to WinCC; non-OS variables have the field permanently disabled.
What authorization level corresponds to standard process operation in PCS 7?
Authorization Level 5 (Process Controlling) is standard for routine operator changes.
What authorization level corresponds to supervisor or engineering changes?
Authorization Level 6 (Higher Process Controlling) or customized higher levels (e.g., Level 1100).
Where are user authorizations configured on the WinCC OS?
In the WinCC User Administrator editor on the Engineering Station / OS Server.
Can I change the Op_Level attribute directly in CFC without modifying SCL?
Yes, once enabled by correct SCL syntax, the numerical authorization level can be customized per instance in CFC pin properties.
Does modifying Op_Level require an AS-OS compilation?
Yes, authorization mappings are compiled into the WinCC tag dictionary and faceplate properties during OS compilation.
What happens if a parameter has S7_m_c = true but no Op_Level defined?
The parameter defaults to the standard authorization level defined by the block type (typically Level 5 or Level 1).
Can output pins have operator level authorizations?
Only output pins that are configured for operator monitoring or manual override support operator authorization settings.

Technical References

SIMATIC PCS 7 CFC for S7 / PCS 7 Manual (V9.0 / V9.1)
SIMATIC S7-SCL V5.6 for S7-300/400 Manual
Siemens Industry Online Support Entry: Op_Level and S7_m_c Attributes (Entry ID 299451)
SIMATIC HMI WinCC V7.5 User Administrator System Manual