Identifying Profibus Alarm Origin Between CEMAT C_DRV_1D, SIMOCODE, and SINAMICS Blocks and Interpreting Status Codes

In SIMATIC PCS 7 CEMAT applications, the generic alarm text 'Profibus' is generated when cyclic DP communication with a motor feeder or variable speed drive is interrupted. To determine whether the alarm originated from the SIMOCODE block (C_SIMOS / C_SIM__A) or SINAMICS block (C_SINA), inspect the 'Block Type' and 'Message Tag' columns in the CEMAT Alarm List or WinCC AlarmControl. On the C_SIMOS block, input SIG3 is configured for Profibus/Device fault, whereas on C_SINA, SIG1 or SIG2 handles drive bus communication. In the CEMAT alarm status column, 'C' denotes 'Came In' (active unacknowledged fault), 'G' denotes 'Gone' (condition cleared), and 'Ackr' represents 'Acknowledged' (operator receipt confirmed).

Executive Summary

In cement and minerals plants utilizing Siemens CEMAT with SIMATIC PCS 7, motor drives frequently combine the supervisory drive block C_DRV_1D with specialized field device adapters such as C_SIMOS (for SIMOCODE pro motor management relays) and C_SINA (for SINAMICS frequency converters). When field bus disruptions occur on PROFIBUS DP, both adapter blocks can issue automated alarm notifications via ALARM_8P. Because standard message text often defaults to 'Profibus' across multiple telegram definitions, operators frequently struggle to differentiate the failing device and interpret the cryptic CEMAT status abbreviations 'C', 'G', and 'Ackr'. This guide establishes the diagnostic procedure to identify the generating function block and clarifies status lifecycle indicators.

Architecture and Fundamental Mechanics

The CEMAT drive control architecture utilizes a hierarchical block structure within Continuous Function Charts (CFC). The master drive block C_DRV_1D manages interlocking, start/stop sequences, and operator faceplate commands. Auxiliary blocks C_SIMOS and C_SINA interface directly with the cyclic I/O telegrams of field devices over PROFIBUS DP or PROFINET IO.

Each function block embeds dedicated ALARM_8P instances. When cyclic communication with a field device fails, the AS operating system invokes OB86 (Rack/Station Failure) or OB122 (I/O Access Error). In response, the driver blocks assert specific error flags:
1. C_SIMOS: Maps cyclic communication loss to signal input SIG3 (associated message text typically configured as 'SIMOCODE Profibus Error' or 'Profibus').
2. C_SINA: Maps telegram communication failure or drive fault bit to SIG1 or SIG2 (associated message text 'SINAMICS Bus Fault' or 'Profibus').

Within the WinCC AlarmControl and CEMAT Message System, alarm states transition through three fundamental phases:
- 'C' (Came In / Active): The fault condition transitioned from 0 to 1; the alarm is active and unacknowledged.
- 'G' (Gone / Inactive): The fault condition cleared (returned from 1 to 0), but may remain unacknowledged.
- 'Ackr' / 'Ack': Acknowledgment confirmed by an operator or automated group acknowledgment script.

Step-by-Step Implementation Procedure

Isolate Alarm Origin in WinCC AlarmControl:
a. Open the CEMAT Alarm List on the WinCC OS Client or Server.
b. Right-click the column header and ensure 'Block Type', 'Origin', 'Tag Name', and 'Event' columns are visible.
c. Locate the row showing the 'Profibus' event and inspect the 'Origin' column. An origin containing 'C_SIMOS' indicates the SIMOCODE relay lost DP communication; an origin containing 'C_SINA' points to the SINAMICS inverter.
Verify Block Interface Signals in CFC:
a. In SIMATIC Manager, navigate to the relevant CFC containing the drive hierarchy.
b. Open C_SIMOS and check output 'Fault' and input 'SimosFlt' / 'SIG3'. If SimosFlt is active (1), the SIMOCODE communication watchdog timed out.
c. Open C_SINA and monitor 'Fault' and 'SinaFlt' / 'SIG1'. If active, the drive communication telegram is invalid or offline.
Diagnose Physical PROFIBUS DP Network:
a. Open STEP 7 Hardware Configuration (HW Config) and select 'PLC -> Diagnostic Buffer' to inspect OB86 station failure events.
b. Check the DP address of the affected device and inspect the diagnostic repeater or bus connector LEDs (BF/SF on SIMOCODE pro V or SINAMICS CU240/CU320).
c. Verify termination resistors at both physical ends of the PROFIBUS segment.
Normalize Message Text Formatting:
a. In SIMATIC Manager, right-click C_SIMOS in the block folder, select 'Special Object Properties -> Message...', and customize the message identifier to 'SIMOCODE DP Comm Fault' to prevent future ambiguity.
b. Recompile CFC charts and execute an OS delta compilation.

Verification

In WinCC AlarmControl, trigger a communication test or observe the live alarm list: verify that incoming faults display with status 'C'.
Acknowledge the alarm via the operator faceplate or CEMAT group acknowledgment button and confirm the status transitions to 'Ackr' or 'C/Ack'.
Restore physical DP communication: verify that the alarm clears with status 'G' and leaves the active alarm list.
Check the CPU Diagnostic Buffer to confirm OB86 outgoing events correspond to normal operating status.

Limitations and Operational Precautions

Changing standard CEMAT block message texts in the block folder requires a complete CFC chart compilation and WinCC OS compilation. If C_DRV_1D is configured to auto-acknowledge auxiliary blocks via AckOp, alarm acknowledgment sequences may clear rapidly without operator intervention. When both C_SIMOS and C_SINA are instantiated on the same drive (e.g., bypass contactor alongside frequency converter), ensure unique technological block comments are assigned to differentiate alarms in the Plant Hierarchy.

Engineer FAQ

What does the status 'Ackr' represent in CEMAT alarm windows?

'Ackr' is the CEMAT abbreviation for 'Acknowledged' (Quittiert), indicating that an operator or system logic has acknowledged an active or cleared alarm.

Why do both C_SIMOS and C_SINA show 'Profibus' alarms simultaneously?

If a physical segment failure, severed bus cable, or powered-down motor control center (MCC) bucket affects both devices on the same DP bus segment, both blocks trigger communication timeout alarms simultaneously.

Can C_DRV_1D suppress SIMOCODE communication alarms during maintenance?

Yes. Setting the test mode or maintenance bypass parameter on C_DRV_1D or isolating the SIMOCODE block via input parameters suppresses interlock trips, though standard ALARM_8P events must be handled via message masking.

How can I distinguish multiple SIMOCODE alarms on the same drive?

By reviewing the 'Message Tag' and 'Event Text' in WinCC AlarmControl, which detail specific telegram bits such as overload trip, phase imbalance, or cyclic communication failure.

Does CEMAT require specific OS Project Editor settings for alarm status display?

Yes. The CEMAT OS Project Editor must be run to apply CEMAT standard layouts and extended alarm line configurations that render 'C', 'G', and 'Ackr' status columns.