SINAMICS S120: Replacing Default External Alarm Captions on AOP30

1. Problem Overview

On the SINAMICS S120 modular drive system, the AOP30 (Advanced Operator Panel 30) displays every drive-side fault and warning using a text string baked into the S120 firmware. The message numbers and their default labels look like this on the panel:

• External alarm 1, External alarm 2, External alarm 3
• External fault 1, External fault 2, External fault 3

Field engineers regularly need to replace these generic strings with operator-readable captions such as "Ventilation fan tripped", "Coolant pressure low", or "Cabinet over-temperature". The panel's own menu does not contain any entry that accepts a user-defined string for these system messages, and there is no parameter slot inside the S120 firmware that maps an arbitrary text to the external alarm numbers.

This article explains the root cause, maps the S120 parameter addresses that trigger the alarms, and presents three field-proven workarounds: a SIMATIC HMI integration over PROFINET, an offline text overlay inside Starter / Startdrive, and a PLC-triggered custom message approach. A commissioning procedure and verification checklist are provided at the end.

2. Why the AOP30 Cannot Customize These Captions (Root Cause)

The text shown on the AOP30 is read from the localized message catalog compiled into the SINAMICS firmware image (file sl.bin or the language-specific *.lg files). Each fault and warning number is hard-coded to a fixed text string inside that catalog:

• A07850 → External warning 1
• A07851 → External warning 2
• A07852 → External warning 3
• F07860 → External fault 1
• F07861 → External fault 2
• F07862 → External fault 3

The AOP30 has no edit field, no script engine, and no XML import routine that can patch these catalog entries at runtime. Its front-end firmware (version 1.x shipped with early CU320-2 builds; version 2.x shipped from S120 firmware V5.1 onward) only consumes the read-only message stream that the Control Unit broadcasts. Because the strings are not parameters and are not exposed through any index in the parameter list, they cannot be edited via p-parameters, parameter sets, or DCC charts.

3. SINAMICS S120 External Fault and Warning Parameter Map

The signals that latch the external faults and warnings are normal CU320-2 BICO inputs. Knowing these addresses is mandatory because every workaround below still has to wire the same trigger source - only the displayed text changes.

Related acknowledgment and reaction parameters (also present in the catalog):

• p2103[0...n] – BI: 1st acknowledge faults (e.g., wire to a digital input or a PLC bit)
• p2104[0...n] – BI: 2nd acknowledge faults
• p2105[0...n] – BI: 3rd acknowledge faults
• p2122[0...n] – CI: Alarm signal source (polled alarms, used for diagnostic evaluations)

The message-type-change feature lets you change the reaction of an existing message but not its text:

• p2118[0...63] – Change message type, message number
• p2119[0...63] – Change message type, new type (1 = fault, 2 = warning, 3 = info)
• p2120 – Change message type, counter (number of active changes)

4. Solution Path 1 — SIMATIC HMI Integration with PROFINET

This is the recommended path when the cabinet already contains a SIMATIC HMI (Comfort Panel, KTP1200, IPC, or Unified Comfort Panel). The HMI reads the S120 fault/alarm buffer via PROFINET / PROFIdrive and renders operator-defined text strings from the WinCC alarm log.

4.1 Topology

The S120 CU320-2 or CU310-2 connects to the HMI as a PROFINET IO device. The PLC (S7-1500 / S7-1200) is not strictly required for alarm display — the HMI can read the drive's diagnostic buffer directly through PROFIdrive acyclic services — but in practice the PLC is in the loop because most external alarm triggers originate from PLC I/O.

4.2 Procedure

1. In TIA Portal, add the SINAMICS S120 device from the hardware catalog (PROFINET IO → Drives → Siemens AG → SINAMICS → S120 CU320-2 PN or S120 CU310-2 PN). The GSD file is bundled with TIA Portal V16 or later; for older versions download it from the Siemens Industry Online Support portal.
2. Configure the PROFINET device name on the CU320-2 with the PRONETA tool or via Starter → Online → Accessible nodes.
3. Drag a SIMATIC HMI device into the project (e.g., 6AV2 124-1MC01-0AX0 KTP1200 Comfort or 6AV2 124-1QC02 12" Comfort Panel).
4. Open the HMI alarm configuration: HMI Tags → Connections → PROFINET (S7). Enable the alarm acquisition mode "S7 Diagnostic Alarms" if you want the drive's fault buffer to surface automatically, or use "Discrete Alarms" if you want to drive alarm classes manually.
5. Create one alarm class per severity: Errors, Warnings, Information.
6. Define one Alarm record per external event. Each record holds the operator-readable text:

7. Wire the HMI tags to PLC bits that are toggled from the same physical inputs that feed the S120's BICO inputs (p2112...p2114, p2106...p2108). You can keep the S120 BICO trigger active (so the drive still reacts correctly), and mirror the same signal into the PLC for the HMI text.
8. Compile the HMI project and download to the panel. Test by forcing each input.

5. Solution Path 2 — Offline Text Overlay in Starter / Startdrive

Siemens commissioning tools allow engineers to attach a free-text comment to a parameter inside the project tree. The comment is stored in the offline project (and inside the saved parameter backup), but not transferred to the drive or to the AOP30. It serves as a commissioning aid only.

1. Open the S120 project in Starter (legacy for firmware ≤ V5.2) or Startdrive inside TIA Portal (firmware V5.1+).
2. Navigate to Drive → Inputs/Outputs → External faults/warnings.
3. Right-click the parameter (for example p2106) and select Properties → Comment.
4. Type the operator-readable string: External fault 1 — Ventilation fans trip.
5. Save the project. The comment is exported to the *.par backup file and the project's *.sdproj archive.

This text is visible to anyone who later opens the same offline project, but it does not appear on the AOP30. Treat it as documentation, not as a runtime caption.

6. Solution Path 3 — PLC-Triggered Custom Messages via WinCC

When the plant already has an S7 controller and a SIMATIC HMI, the cleanest approach is to skip the S120 external alarm mechanism entirely and let the PLC raise a WinCC alarm directly. The S120 BICO trigger is still wired, but the visible text comes from the WinCC alarm buffer.

6.1 SCL / Structured Text example (S7-1500 / S7-1200)

// Custom alarm latches for SINAMICS S120 external events
// Inputs come from the same field terminals that also drive p2112..p2114 / p2106..p2108

#iVentTrip       BOOL;     // ventilation contactor feedback
#iCoolantLow     BOOL;     // pressure switch, 1 = low
#iDoorOpen       BOOL;     // cabinet door limit switch

// Latch rising edges so the HMI shows the alarm until acknowledged
IF #iVentTrip THEN
    "dbExtAlarm".VentTrip := TRUE;
END_IF;
IF #iCoolantLow THEN
    "dbExtAlarm".CoolantLow := TRUE;
END_IF;
IF #iDoorOpen THEN
    "dbExtAlarm".DoorOpen := TRUE;
END_IF;

// Acknowledge from HMI button (resets all three)
IF "dbHMI".btnAckExt THEN
    "dbExtAlarm".VentTrip   := FALSE;
    "dbExtAlarm".CoolantLow := FALSE;
    "dbExtAlarm".DoorOpen   := FALSE;
END_IF;

Each bit in dbExtAlarm becomes a WinCC alarm tag. Configure the matching alarm records in WinCC with the operator-readable text strings shown earlier.

6.2 Retaining the S120 reaction

Keep the BICO wiring to p2106 through p2108 and p2112 through p2114 intact. The S120 will still execute the configured OFF reactions (default: OFF1 / OFF2 with ramp stop). The PLC mirror bit is used only for the display layer. Both must be acknowledged independently: the S120 fault via the AOP30 ACK key or via p2103, and the WinCC alarm via the HMI button.

7. AOP30 Hardware and Firmware Considerations

The AOP30 always receives the firmware-resident text from the CU320-2 / CU310-2, regardless of its own firmware level. Updating the AOP30 firmware (delivered through the S120 commissioning package) does not unlock editable captions; it only adds new menu items and fixes bugs. The behavior described in this article is the same across all AOP30 firmware revisions currently in circulation.

8. Commissioning Procedure (Step-by-Step)

This is the recommended sequence when adopting Solution Path 1 (SIMATIC HMI).

1. Wire the field device. Connect the alarm source to both the PLC digital input (for HMI display) and the S120 BICO terminal / DI on the Control Unit (for drive reaction).
2. Configure the S120 BICO. In Starter / Startdrive, set p2106[0] = the source for external fault 1, p2107[0] for external fault 2, p2108[0] for external fault 3, and p2112[0] through p2114[0] for the three external warnings. Save the project to RAM and ROM.
3. Verify the drive reaction. Force each input and confirm the S120 trips with the corresponding F07860 – F07862 / A07850 – A07852 message visible on the AOP30. Acknowledge to clear.
4. Configure the PLC tag. In the S7 program, mirror each input into a dedicated bool or word tag inside the shared DB.
5. Add the HMI connection. In TIA Portal, add an HMI connection of type S7-1500 / S7-1200 with the same PROFINET subnet. No special driver is needed.
6. Create the alarm records. In the HMI editor, add one discrete alarm per event with the operator text.
7. Compile and download. Download the PLC hardware configuration first, then the HMI project.
8. Acceptance test. Force every input; confirm the operator text on the HMI matches the design, and confirm the S120 still reacts as specified.

9. Verification Checklist

10. Troubleshooting Matrix

11. FAQ