The C264 uses structured databases to manage data. The main principle is that the computer will only operate with other PACIS devices if their database versions are identical.
A database (DB) is a file that includes the description of the whole of the electric process, and all of the devices that the computer is likely to communicate with: IED, HMI, and so on.
The database also includes some parameter settings for the software and for the transmission protocols. Use a separate PACiS tool, the System Configuration Editor (SCE), to create and version the databases. Each database has a related VDBS (System Baseline Version).
You can download a standby database even if the computer is in operation: use the filename.adb format.
You can download a database into the flash memory of the computer in two ways:
• Use the PACiS tool, the System Management Tool (SMT) to download the database thru the IEC61850 station bus (SBUS).
• Use the PACiS tool, the Computer Administration Tool (CAT), to download the database directly over Ethernet. Operators generally use the CAT only for the download of the first database. During the download, the CAT sends the database to all of the other racks. This database becomes the new Standby database. At the Switch command, the computer cascades the switch operation to the other racks.
From SCADA, the C264 receives the database file and saves it in RAM, but does not send it to the other racks.
On the C264, the database status shows only on the main rack LCD.
The main 1 rack does a check for the compatibility between its database and the database installed in the main 2 rack and in the extension racks. It the databases are different, the main 1 rack has the most recent version and deletes the databases on the other racks.
If the main database on the main 1 rack is compatible with the standby database on the other rack, the computer switches the database.
At any moment, the computer stores as many as two DBs in its flash memory. The two DBs and their related VDBS have the labels DB1, VDBS1; and DB2, VDBS2.
Each database of the computer, DB1 and DB2, has one of the states that follow:
• Missing: the DB is not present in the flash memory of the computer
• Standby: the DB was downloaded into the non volatile memory of the computer, but the software does not acknowledge this version
• Current: the software acknowledges the downloaded DB
• Current Modified: the DB had a change to a parameter setting and the software currently acknowledges the DB
• Standby Modified: the DB had a change to a parameter setting and the software does not acknowledge the DB.
In the computer, the life cycle of the DBs shows in the figure that follows:
C0308ENa
Standby Switching Current
Standby Modified
Parameter setting
Current Modified Switching
Downloading Absent
Parameter setting
FIGURE 2: THE DIFFERENT STATUS OF A DATABASE
At any moment, there is only one DB either in the Current state, or Current Modified state.
In the same way, there is only one DB either in the Standby state, or Standby Modified state.
For the two downloaded DBs, DB 1 and DB 2, the four possible states show in the table that follows:
Database State 1 State 2 State 3 State 4
DB1 and VDBS1 Current Current Modified Current Current Modified DB2 and VDBS2 Standby Standby Standby Modified Standby Modified
A file descriptor with the label DB context, stored in the flash memory of the computer, includes the configuration of the DB installed on the device. This file descriptor, that includes the state of each of the two databases and their related VDBS (for example, DB1 and VDBS1; DB2 and VDBS2), allows you to know the configuration of the databases at the moment of the computer boot (initialisation mode), and to start again with the Current database, if it exists. To update the file descriptor DB Context, use these functions:
• Download a database
• Switch the databases
• Check a database
• Modify a Database.
2.2.2 How to download a database through the Ethernet
Connect the computer to the station bus (SBUS). Use the SMT tool to download the first DB.
The first time that you download the DB and the related Vdbs, make sure that the computer is in maintenance mode.
When the computer operates with the first DB, and the computer is either in operational mode or in maintenance mode, you can download the standby DB and its related Vdbs.
The sequence to download the DB follows:
1. Use the PACiS SMT tool to send a request to start the transfer of the database.
2. The receiver, the PC, gives a positive response.
3. Transmit the response to the device that called. If another request on the same DB is already in progress, the device will refuse your request.
4. Download the DB file and the related Vdbs. The computer does a check of the integrity of the files: it calculates the checksum and control of the DB
5. In event of a fault, the computer sends a signal to announce the failure of the transfer, to the device that called
6. In event of a successful transfer of the DB, the computer controls the DB compatibility 7. In event of an invalid DB, the computer sends a signal to announce the failure of the
DB installation, to the device that called 8. In event of a valid DB, the computer:
− Removes a possible standby DB and related Vdbs already installed in the computer
− Assigns the state standby to the downloaded DB and related Vdbs installed in the computer
− Sends a signal to announce the success of the DB installation to the device that called.
9. The computer updates the file descriptor, Context DB, in flash memory.
2.2.3 How to switch the databases
The SBUS sends a request to switch the DB. This request specifies the Version of the standby DB and related Vdbs to become current. Please refer to Figure 4: Database Download and to Figure 5: Database Switching
C0309ENa Vdbs n.m
DB1
Vdbs x.y
DB2
CURRENT STANDBY
Vdbs x.y
DB2
Vdbs n.m
DB1
CURRENT STANDBY
SWITCH
MAINTENANCE MAINTENANCE
T0 T0 + T1
Vdbs x.y
DB2
Vdbs n.m
DB1
CURRENT STAND-BY
OPERATIONAL T0 + T1
T0 + T1
FIGURE 3: DATABASE SWITCHING
FIGURE 4: DATABASE DOWNLOAD
After a successful database download, the SCADA sends the switch command with the “Reset process command” standard message (ASDU 105) to the computer.
When the computer receives the switch command, the computer downloads the database to the other racks. Please refer to Figure 5: Database Switching
FIGURE 5: DATABASE SWITCHING
When this series of downloads is successful, the computer switches the databases in all the racks.
After a DB switch, and if the DB is coherent with the software, the computer automatically reboots and goes into Operational Mode.
2.2.4 How to do a check of the database
At each reboot, the computer does a check of the DB.
With the C264 local Operator Interface, with the Human Machine Interface (HMI) front panel, or with the maintenance laptop computer and the Computer Administration Tool (CAT), you can set the time and date.
2.2.5 How to modify the database
With the local HMI, you can only modify a parameter setting on the current DB: that is, the Current or Current Modified DB. You can modify only certain data parameters. To modify the parameters of the DB, you modify some configuration values in the DB. The modified DB stores the new parameter settings. The computer increments the internal index of the parameter setting file and calculates again the checksum of the file. The database takes the Current Modified state.
2.2.6 How to modify a parameter setting in the current DB
To modify the parameter setting in the current DB, use the computer to:
1. Do a check of the coherence of the request:
− Is the object known to the computer, that is, is the object really present in the database
− Can the computer set the data
− Is the value of the parameter setting compatible with the type of data conveyed:
does the value belong in the range of acceptable variation
2. If the request is incoherent, the computer sends a negative report to the device that sent the request.
3. Write the current value of the data in the DB 4. Write the date that you modified the data in the DB 5. Compute the checksum and to write it in the DB 6. Assign the state Current Modified to the DB
7. Send a positive report to the device that sent the request
8. Update the file descriptor, that is the Context database, in the flash memory 2.2.7 How to consult a parameter setting
To manage a request to consult a parameter setting in the current DB from the Operator Station, use the computer to:
1. Do a check of the coherence of the request:
− Is the object known to the computer, that is, is the object really present in the database
− Can the computer set the data
− Is the value of the parameter setting compatible with the type of data conveyed:
does the value belong in the range of acceptable variation
2. If the request is incoherent, the computer sends a negative report to the device that sent the request:
3. Develop the response to include the parameter setting and to send it to the device that sent the request
For the C264 , you can use the Computer Administration Tool (CAT) to upload and store a DB as large as 20 MB in the flash memory.