Starting in AX-3.2, server-side support was added for the BACnet DM-BR-B BIBB, such that a remote BACnet Workstation client can backup and restore the configuration of a station running on a JACE host. Several related properties were added to the LocalBacnetDevice, as shown in Figure 103.
The following descriptions apply to these properties:
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Last Restore Time — Timestamp of when a backup .dist file was last restored by a remote BACnet Workstation client. If never, all timestamp fields show asterisks (*).
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Backup Failure Timeout —(Default is 3 minutes). Specifies the time the server device must wait before deciding that the client has given up, and can leave backup/restore mode. The client typically writes this to the server prior to beginning the backup/restore procedure.
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Backup Preparation Time — (Default is 1 minute). Specifies the time allotted for the station, after receiving the backup request, to locally save the station database. May need to be increased in the case of a large station.
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Restore Preparation Time — (Default is 1 minute). Specifies the time allotted for the station, after receiving a restore request, to gracefully shut down the station and close files before beginning the dist file installation. May need to be increased in the case of a large station
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Restore Completion Time — (Default is 3 minutes). Specifies the time allotted for the station, after completing a dist file install from a restore, to restart and become responsive. May need to be increased in the case of a large station.
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Backup and Restore State — (read-only) Shows the current backup and restore state, where “Idle” is shown when no operation is active. This can change to “Preparing for backup” and so forth.
Properties above were defined in a recently accepted proposal to the SSPC to fix known issues with the backup and restore
feature, as currently defined in the spec. The proposal will be the subject of a future public review document, but it will
likely be accepted, and so it has been implemented for now. When the document becomes an official part of the standard, there
will likely be an update patch to adjust the property identifier indices.
See the next section, About backup and restore operations, for additional details.
Any backup or restore initiated from a remote BACnet Workstation client requires several things before it is acted upon by the station, as follows:
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The station user “BACnet” requires admin-level write permissions on the BacnetNetwork and BacnetLocalDevice, at a minimum. The password for the BACnet user must be a non-blank (non-default) value, and this password must be known to the operator of the remote BACnet Workstation.
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The normally-hidden “Reinitialize Allowed” property of the Server layer component (child of the BacnetComm container under the BacnetNetwork) must be unhidden and set to a value of “true,” as it defaults to “false.” Once changed, it can be rehidden if desired. See About Bacnet Comm: Client, Server, and Transport for related details.
If the conditions above are met, and if an AX-3.2 or later station receives a backup or restore request, these operations occur as described below:
Backup and restore procedures used adhere to Clause 19 of the BACnet Specification.
Backup operation proceeds as follows:
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The LocalBacnetDevice’s “Backup and Restore State” property changes from “Idle” to “Preparing for backup.”
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The station’s BackupService begins preparing a backup .dist, containing the following:
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The assembled backup .dist file is then exported as a File object and is part of the configurationFiles property of the device object. The backup client then reads the File object using BACnet file access services.
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The LocalBacnetDevice’s “Backup and Restore State” property changes back to “Idle,” and normal station operation resumes.
Restore operation proceeds as follows:
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The LocalBacnetDevice’s “Backup and Restore State” property changes from “Idle” to “Preparing for restore.”
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The station begins a graceful shutdown, saving opened files.
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The backup .dist file is sent from the remote BACnet Workstation client to the JACE platform.
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The backup .dist file is installed, and then the JACE host rebooted.
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Upon station startup, the LocalBacnetDevice’s “Backup and Restore State” property changes back to “Idle,” the “Last Restore Time” reflects the time of the backup .dist installation, and normal station operation resumes.