ABB OCAHG 492838402 Management Controller Application

The provided text offers comprehensive guidelines for managing memory usage in controller applications, particularly in systems that perform online updates. Here’s a structured breakdown of the key points based on OCAHG 492838402:

1. Memory Usage Limit:
   • It’s recommended that applications should not exceed half of the available memory size to ensure efficient processing of online updates.
2. Online Update Process:
   • Modifications made to the application program are downloaded to the controller’s memory.
   • A new version of the application is created in the controller’s memory based on old applications and modifications.
   • The controller switches from the old application to the new application.
   • The old application is deleted.
3. Updated Memory Requirements:
   • Adequate available memory, equivalent to the maximum application size, is necessary to accommodate the update. If the application approaches this limit, it should be divided into smaller parts for separate updates.
4. Spare Memory for Online Changes:
   • Online changes require at least 20% spare available memory. However, depending on factors like application complexity and defined alerts, this may require up to 50% available memory.
5. Monitoring Memory Usage:
   • The “SystemDiagnostics” function block provides a “maximum memory usage” number, indicating memory usage as a percentage of bytes and memory size. This aids in determining the proximity to the memory limit for online changes. Multiple online changes are necessary to ascertain the maximum memory requirement in the controller.
6. Online Change Possibility:
   • Online changes remain possible as long as the “maximum used memory” value remains below 100%.
7. Memory Report:
   • While the “System Diagnosis” function block reports used memory based on memory size, the “Heap Utilization” dialog box displays available memory as “Unused Heap”.

In summary, effectively managing memory usage is crucial for ensuring smooth online updates in controller applications. Adhering to recommended memory limits and diligently monitoring memory usage can contribute to efficient system operation and maintenance.