When updating a PLC—whether upgrading the operating system or deploying a new application project—preserving all critical data is essential to ensure a smooth restart and avoid unexpected machine behavior.
This guideline summarizes the key areas that must be secured before performing any update on a B&R system.
1. Backup of Retentive Variables (PV)
Retentive variables store essential runtime information such as counters, production values, calibration offsets, and machine states.
In B&R systems, backing up PVs depends on the mechanisms provided by the application and the runtime environment.
Before performing the update:
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Check whether the application includes a dedicated PV backup/restore routine (e.g., exporting PV sets to files).
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If no application-level backup exists, a fallback strategy can be used:
restart the PLC in Service Mode and export all PVs whose value is different from zero.
This captures meaningful runtime data while avoiding default‑initialized values. -
Verify that the exported PV file is complete and readable.
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If the update introduces structural changes to PVs, validate compatibility before restoring.
This ensures that the machine can resume operation with the correct internal state after the update.
2. Backup of NON_VOLATILE Retentive Configuration
In B&R systems, NON_VOLATILE data areas do not have a built‑in system-level backup function.
A backup is only possible if the application explicitly implements a mechanism to export, store, and restore these data blocks.
Typical NON_VOLATILE data include:
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Machine configuration parameters (such as Ethernet settings)
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Calibration or tuning values
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User-defined settings
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Persistent configuration structures
Before performing the update:
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Verify that the application provides a method to export NON_VOLATILE data (file storage, service commands, custom routines).
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Use the application’s backup function to generate a complete and up‑to‑date copy of all NON_VOLATILE data.
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Confirm compatibility with the target software version, especially if data structures have changed.
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Ensure that the restore procedure is documented and validated.
This prevents misconfigurations or unexpected behavior after the upgrade.
3. Backup of CompactFlash (CF) Content
The CompactFlash card often contains essential runtime components, including:
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System files
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Application data
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Logging directories
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Custom configuration files
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Additional software modules
To avoid accidental data loss:
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Perform a complete CF image backup before starting the update.
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Validate the integrity of the backup (e.g., checksum or file comparison).
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Document the CF structure to support accurate manual restoration if needed.
A CF backup is especially important when updating the operating system or when the update procedure involves formatting or replacing the storage media.
4. Data Objects Modified in Retentive Areas but Not Yet Saved to CF
Many applications use Data Objects to store structured configuration data, recipes, or calibration sets.
When these Data Objects reside in retentive memory, runtime modifications may not be immediately written to CF.
During an update, any unsaved changes stored only in RAM will be lost.
Before performing the update:
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Check whether the application provides an explicit save mechanism for Data Objects.
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Ensure that all modified Data Objects are saved before shutting down the system (e.g., via a “Save All” or “Commit Changes” function).
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If no save mechanism exists, consider a fallback approach:
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Restart the PLC in Service Mode.
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Export the Data Objects directly from the runtime environment, if supported.
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Verify that the exported files reflect the latest runtime modifications.
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Document which Data Objects are expected to be persistent and confirm that their save logic is correctly implemented.
This step ensures that no runtime modifications are lost simply because they were never committed to non‑volatile storage.
Final Recommendations
To minimize risks and ensure a safe update process:
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Always perform all four backup steps before updating the PLC.
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Store backups in a secure, versioned repository.
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Validate restore procedures in a controlled environment whenever possible.
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Maintain clear documentation of the system configuration and backup strategy.
Following these guidelines helps ensure predictable, reversible, and safe update procedures for B&R systems.
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Additional content and resources, both directly and indirectly related to this topic, can be found in the following Community posts:
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General PLC Backup:
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How to take Backup from PLC X20CP1584 – Discusses using Runtime Utility Center to upload global/local PVs for backup. [community…mation.com]
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Can I get backup image from PLC with internal memory? – Mentions using MpBackup for project backup and restore. [community…mation.com]
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Retain Variables & Runtime Settings:
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How to save a variable value after controller power off inquiry – Covers issues with RETAIN variables not persisting after power cycles. [community…mation.com]
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Easy and quick way to save/restore values of permanent variables – Suggests using Runtime Utility Center and variable lists for saving/restoring permanent variables. [community…mation.com]
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Retain Tag and Remanent Memory Usage – Discusses remanent memory and retain tag behavior. [community…mation.com]
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Consider this an evolving resource: your feedback, suggestions, and shared experiences will help shape and enrich it over time.
