C135 PCS 7 (PCS7)
6C
6 Cielo Ciencia y Tecnología
·Publicada en C135 PCS 7 (PCS7)

Resolving CPU 410-5H Redundancy Warning - Data Block Work Memory Allocation Mismatch in H-Parameters

Resolving CPU 410-5H Redundancy Warning - Data Block Work Memory Allocation Mismatch in H-Parameters

When downloading to a redundant SIMATIC S7-400H or CPU 410-5H controller, the warning 'The specification of the work memory assignment of all data blocks of your program in the object properties of the CPU (H-Parameters tab) does not correspond to the current state' occurs when the user data block work memory defined in HW Config is smaller than the actual compiled DB memory in the AS program. In redundant systems, this value determines the maximum update and synchronization monitoring times during standby CPU updating (HCiR). To resolve the warning, open HW Config, access CPU Properties > H-Parameters, click 'Calculate', update the DB work memory allocation to match or slightly exceed the actual value, click 'Recalculate', save/compile HW Config, and download the hardware configuration to the AS.

Table of Contents

Executive Summary

High-availability automation with redundant SIMATIC S7-400H and CPU 410-5H systems requires precise mathematical modeling of memory synchronization to guarantee seamless bumpless switchover and online configuration changes in RUN (H-CiR). During the compilation and download of charts or hardware configurations, engineers frequently encounter a system warning indicating that the configured data block work memory allocation (e.g., 1024 kB) in the CPU's H-Parameters tab is lower than the actual compiled user program memory (e.g., 2220 kB). This discrepancy compromises the CPU operating system's calculation of monitoring times (Überwachungszeiten beim Aufdaten der Reserve CPU). This technical guide details the synchronization mechanics, the operational risks of ignoring the warning, and the exact step-by-step procedure to recalculate and eliminate the mismatch.

Architecture and Fundamental Mechanics

Redundancy Synchronization and DB Work Memory Mechanics

In a redundant S7-400H / CPU 410-5H architecture, both CPUs execute user logic in event-synchronized lockstep. When a standby CPU is coupled (during initial power-on or following an H-CiR modification), the operating master CPU must transfer the entire dynamic state of the user process to the standby CPU via high-speed fiber-optic synchronization modules.

+-----------------------+                         +-----------------------+
|      Master CPU       |   Fiber-Optic Sync      |      Standby CPU      |
|     (CPU 410-5H)      |========================>|     (CPU 410-5H)      |
|                       |   Dynamic DB Transfer   |                       |
| [Compiled DBs: 2220KB]|                         | [Sync Verification]   |
+-----------------------+                         +-----------------------+
           |
           v
+-------------------------------------------------------------------------+
| HW Config H-Parameters Dialog:                                          |
| Configured DB Work Memory: 1024 kB  <-- [UNDERSIZED CONFIGURATION]      |
| Actual DB Work Memory:     2220 kB                                      |
|                                                                         |
| Result: Operating system calculates insufficient sync timeout!          |
| Warning: 'Die Angabe der Arbeitsspeicherbelegung aller Datenbausteine...'|
| Risk: Cycle time overrun or CPU STOP during standby coupling / H-CiR    |
+-------------------------------------------------------------------------+

Key synchronization parameters configured in the H-Parameters tab include:
1. Work memory allocation of all data blocks: Represents the total RAM occupied by all data blocks (system DBs, CFC chart instance DBs, and user DBs) that must be serialized and copied across the fiber link.
2. Maximum cycle time extension: The maximum delay tolerated by the running process during the memory transfer phase.
3. Standby CPU Updating Monitoring Times: The maximum time allowed for memory copy before the master decides whether coupling succeeded or aborts to protect process cycle execution.

If the actual DB size is 2220 kB but the H-Parameters tab assumes only 1024 kB, the CPU calculates an underestimated monitoring time window. If field communication or heavy CPU load occurs during coupling, the transfer exceeds the underestimated window, triggering an unbumpless abort or forcing the standby CPU into STOP.

Step-by-Step Implementation Procedure

Step 1: Identify the Actual DB Work Memory Allocation

  1. In the Step 7 warning dialog displayed during download, note the exact values reported: (Configured: XXXX kB, Actual: YYYY kB). In this scenario, Actual = 2220 kB.
  2. Alternatively, in SIMATIC Manager, select the S7 Program block container, right-click and select Block Counts / Program Statistics, and view the total work memory consumed by DBs.

Step 2: Open CPU Properties in HW Config

  1. In SIMATIC Manager, open the Hardware configuration editor for the redundant AS station.
  2. Double-click the Rack 0 CPU (CPU 410-5H or CPU 417-5H) to open Object Properties.
  3. Select the H-Parameters tab.

Step 3: Recalculate Monitoring Times

  1. In the H-Parameters tab, locate the group Monitoring Times During Standby CPU Updating.
  2. Click the Calculate... (or Berechnen...) button.
  3. In the calculation dialog, locate the parameter field Work memory allocation of all data blocks in the user program (Arbeitsspeicherbelegung aller Datenbausteine im Anwenderprogramm).
  4. Enter the actual value reported by the warning (e.g., 2220), or enter a slightly higher value (e.g., 2400 or 2500 kB) to provide headroom for future CFC additions.
  5. Click the Calculate (or Neu berechnen) button within the dialog. Step 7 will automatically recalculate the recommended monitoring times and maximum cycle time extension based on controller processing speed and bus load.
  6. Click OK to close the calculation dialog, then click OK to close CPU Object Properties.

Step 4: Synchronize Rack 1 CPU and Compile HW Config

  1. If configuring a redundant station, verify that the H-parameter settings automatically propagated to the redundant partner CPU in Rack 1.
  2. In HW Config, execute Station > Save and Compile.

Step 5: Download Configuration to the AS

  1. In HW Config, click Download to Module.
  2. In redundant systems operating in RUN, execute the download using the standard redundant download procedure (Download to CPU with modified configuration / H-CiR sequence) or download during a scheduled maintenance window.
  3. In SIMATIC Manager, perform a delta or full chart download: Target system > Download to target system > Changes Only.
  4. Verify that the work memory warning no longer appears during compilation or download.

Verification

  1. Download Verification: Initiate a chart download (Changes Only) from CFC or SIMATIC Manager. Confirm that the download dialog executes to completion with zero warnings regarding DB work memory.
  2. Diagnostic Buffer Inspection: Open the module information (Ctrl+D) for both Master and Standby CPUs. Verify that event ID 16#45 and synchronization events indicate clean lockstep coupling without timing warnings.
  3. H-CiR Validation: If testing in a staging environment, perform a manual CPU failover or test an online change in RUN to ensure bumpless synchronization without cycle time watchdog faults.

Limitations and Operational Precautions

  1. Maximum Cycle Extension Trade-Off: Increasing DB work memory values may result in the calculator recommending a larger maximum cycle time extension. On high-speed processes (e.g., compressor anti-surge loops), verify that cycle extension does not exceed maximum allowable valve response latency.
  2. SEC License Constraints: This work memory setting affects synchronization calculation; it does not expand physical RAM or the Process Object (PO) count licensed on the System Expansion Card (SEC).

Engineer FAQ

Does this warning stop the CPU from running?

No. The warning is non-fatal and does not prevent the CPU from entering RUN, but it warns that future standby CPU coupling or H-CiR might fail due to timeout.

Why did the DB work memory increase?

Adding CFC charts, APL blocks, analog alarms, and interlock blocks automatically instantiates new instance DBs in the S7 program, expanding DB work memory.

Should I set the value exactly to the actual size or higher?

Setting it slightly higher (e.g., 10% to 15% above actual) is recommended so that routine logic additions do not immediately re-trigger the warning.

Can I update H-Parameters online in RUN?

Yes, in redundant S7-400H / CPU 410-5H systems, hardware configuration changes can be loaded in RUN using the H-CiR (Hardware Configuration in RUN) wizard.

Does this setting affect single-station non-redundant CPUs?

No. The H-Parameters tab and standby update calculations exist exclusively on redundant H-controllers.

What happens if the synchronization monitoring time is exceeded?

The master CPU aborts the standby update to protect the running process, leaving the standby CPU in STOP and losing redundancy.

Does downloading HW Config with updated H-parameters cause an unbumpless bump?

When executed via standard H-CiR procedures, the switchover is bumpless within the configured maximum cycle time extension.

What is HCiR?

HCiR stands for 'Hardware Configuration in RUN', a Siemens feature allowing hardware modifications and parameter updates without halting the controller.

Where can I see the physical memory card capacity?

In SIMATIC Manager, go to Target System > Diagnostic / Setting > Module Information > Memory tab.

Does this parameter require purchasing additional Siemens licenses?

No. Recalculating internal H-parameter monitoring times is a standard engineering task and requires no additional software or hardware licensing.

Technical References

Related Articles

Related Tags

  • CPU 410-5H
  • S7-400H
  • H-Parameters
  • Work Memory DB
  • HCiR
  • Redundancy Synchronization
  • HW Config
20 respuestas