Enabling Operator-Adjustable Alarm Time Delays on APL MonAnL Blocks in WinCC Faceplates

In SIMATIC PCS 7 Advanced Process Library (APL), when plant operators are unable to modify alarm time delays (Alarmverzögerung) directly from the MonAnL (FB1845) faceplate in WinCC, the cause is either missing operator permissions in OS_Perm, active parameter interconnections in CFC, or lack of authorization Level 6 in WinCC User Administrator. MonAnL incorporates dedicated delay inputs for every limit stage (HH_AlmTiLag, H_AlmTiLag, L_AlmTiLag, LL_AlmTiLag). To grant operator edit authority from the OS faceplate, ensure these parameters are not interconnected in CFC, verify that the logged-on Windows/WinCC user possesses Authorization Level 6 ('Higher process controlling'), and verify that OS_Perm permits limit modifications.

Executive Summary

In process automation sectors such as drinking water distribution, municipal wastewater, and hydraulic networks, fluid pressure lines frequently experience transient pressure waves (water hammer) or brief pump startup fluctuations. Operators require the operational flexibility to adjust alarm delay times directly from the WinCC faceplate to filter out nuisance alarms without contacting an automation engineer to modify CFC charts. However, on standard APL MonAnL faceplates, delay fields often appear read-only or grayed out. This guide explains how alarm delays are parameterized in MonAnL, clarifies faceplate authorization dependencies, and provides solutions to enable dynamic operator adjustments.

Architecture and Fundamental Mechanics

The alarm delay and operator authorization architecture of APL MonAnL (FB1845) operates via structured multi-layer gates:
1. Dedicated Per-Limit Alarm Delays:
Unlike older legacy libraries that provided a single global delay, MonAnL incorporates independent incoming delay timers for each alarm boundary:
- HH_AlmTiLag: High-High Alarm delay time (seconds).
- H_AlmTiLag: High Warning delay time (seconds).
- L_AlmTiLag: Low Warning delay time (seconds).
- LL_AlmTiLag: Low-Low Alarm delay time (seconds).
An alarm is asserted only if the process variable violates the limit threshold continuously for longer than the configured delay time.
2. Interconnection Lockout Rule:
In PCS 7 APL, if any block parameter has an active graphical interconnection in CFC, the block's internal logic marks that parameter as read-only for the HMI. The WinCC faceplate automatically detects the interconnection flag and disables operator entry fields.
3. WinCC Authorization and OS_Perm Dependencies:
- Operating Permission (OS_Perm): Input parameter OS_Perm on MonAnL controls technological operator privileges. If the bit authorizing limit modifications is set to 0, faceplate inputs are blocked.
- WinCC User Administrator: Modifying limit thresholds and delay times in the APL 'Limit View' strictly requires WinCC Authorization Level 6 ('Higher process controlling') or Level 11 ('Process controlling'). Operators with basic view-only authorization cannot edit these values.

Step-by-Step Implementation Procedure

Verify Parameter Interconnections in CFC:
a. Open the CFC chart containing the MonAnL block.
b. Inspect the inputs HH_AlmTiLag, H_AlmTiLag, L_AlmTiLag, and LL_AlmTiLag.
c. Ensure these inputs are not interconnected to another block output.
d. If an input is interconnected, delete the link so the parameter is treated as an operator-controllable value.
Configure Operating Permissions on MonAnL (OS_Perm):
a. Open the Object Properties of MonAnL in CFC.
b. Inspect parameter OS_Perm.
c. Ensure OS_Perm.Bit11 (or the bit governing limit/delay adjustments) is set to 1 (TRUE).
d. Verify that Feature.Bit22 ('Update operating permission in case of change') is set to 1.
Configure WinCC User Administrator Authorizations:
a. On the Engineering Station, open WinCC Explorer and launch 'User Administrator'.
b. Select the operator user group (e.g., Operators or Plant_Engineers).
c. Ensure that Authorization Level 6 ('Higher process controlling') is checked for this group.
d. Save User Administrator settings.
Optional Alternative: Dedicated Operator Analog Input Block (OpAnL):
a. If site conventions require a dedicated faceplate slider or separate operator entry block for plant-wide delay tuning:
b. Instantiate an OpAnL (FB1865) block in the CFC chart.
c. Connect OpAnL.Out to MonAnL.H_AlmTiLag.
d. Operators can then adjust the delay time from the dedicated OpAnL faceplate with full audit trail logging in WinCC.
Recompile OS and Deploy:
a. Compile OS changes in SIMATIC Manager (Compile -> Changes only).
b. Download changes to the OS servers.

Verification

In WinCC Runtime, log in with an operator account assigned Authorization Level 6.
Click the analog transmitter block icon to open the MonAnL faceplate.
Click the 'Limits' button to open the Limit View.
Locate the alarm delay input field next to the High or Low limit: verify that the input box is white (editable) rather than grayed out.
Enter a new delay time (e.g., change from 0.0s to 5.0s) and click OK.
Verify that the new value is accepted, and verify online in CFC test mode that H_AlmTiLag updates immediately.

Limitations and Operational Precautions

Configuring excessively long alarm delays (e.g., > 60 seconds) directly on MonAnL can delay critical trip reporting during genuine catastrophic process excursions; safety-critical shutdowns must rely on dedicated fail-safe interlocks rather than filtered monitoring blocks.

Engineer FAQ

Why is the alarm delay field grayed out in the MonAnL faceplate?

The field is grayed out if the parameter is interconnected in CFC, if OS_Perm blocks operator changes, or if the logged-on user lacks WinCC Authorization Level 6.

What are the parameter names for alarm delays on MonAnL?

HH_AlmTiLag, H_AlmTiLag, L_AlmTiLag, and LL_AlmTiLag.

What WinCC authorization level is required to change alarm delays?

Authorization Level 6 ('Higher process controlling') is standardly required for the Limit View in APL faceplates.

Can I configure different delays for incoming and outgoing alarms?

MonAnL provides standard incoming delay timers (*_AlmTiLag). For outgoing alarm delays, check APL parameter AlarmDelay.Outgoing or use downstream timer blocks.