Redundancy
Redundancy
The Redundancy feature ensures continuous operation of the SCADA system by allowing two servers to back each other up. With this architecture, if the primary server fails, the backup server automatically takes over and the system continues running without interruption.
The Redundancy screen consists of two sections:
- This SCADA (Local Server Settings)
The role and status of the computer you are currently using. - Partners (Backup Server Settings)
The configuration of the remote server that will act as the backup.
1. This SCADA (Local Server Settings)
This row displays the redundancy configuration of the local computer.
| Parameter | Description |
| Symbol | The name assigned to this server (e.g., “This SCADA”). |
| Port | The TCP port used by the local server to listen for redundancy communication (default: 8000). |
| Activate | Starts or stops the redundancy service. |
| Is Primary | (Status) Indicates whether this server is currently acting as the Primary (Master). |
| Connected Server | Shows the server-to-server connection status. |
| Connected Client | Displays the status of client connections over the redundancy link. |
| Enable DB Sync | Enables automatic synchronization of historical data and logs with the backup server. |
| Database | Displays the database name or connection information to be synchronized. |
| Try To Connect | Manually attempts to initiate a connection to the partner server. |
| Verified / Not Verified | Indicates whether redundancy configuration and database synchronization are validated. |
| Comment | A free-text field for custom notes. |
2. Partners (Backup Server Definitions)
This section defines which remote computer will act as the “Partner / Backup” for the local server.
Each row represents a single partner server.
| Parameter | Description |
| No | Index number of the backup server. |
| Symbol | Symbolic name of the backup server. |
| IP Address | IP address of the partner server (e.g., 192.168.1.11). |
| Port | Listening port of the partner server (must match the local port). |
| Period (ms) | Frequency of heartbeat messages (recommended: 1000 ms). |
| Timeout (ms) | Time to wait before the partner is considered offline (recommended: Period × 3). |
| Retry Count | Number of reconnection attempts when communication is lost. |
| Activate | Enables communication with this partner server. |
| Is Primary | (Status) Indicates whether the partner server is currently acting as Primary. |
| Connected | Displays the connection status between servers. |
| Fault | Indicates whether a fault is detected on the partner server. |
| Database | Shows the database synchronization status on the partner side. |
| Try To Connect | Manual connection test. |
| Verify | Validates the configuration of the partner server. |
| Comment | Free-text field for additional notes. |
Failover Operation Scenario
- Both servers run the same SCADA project.
- The primary server communicates with PLCs and sends data to clients.
- The secondary server continuously waits for heartbeat signals from the primary server.
- If the primary server shuts down or no heartbeat is received within the timeout period:
The secondary server automatically becomes the new Primary. - Client workstations reconnect to the new Primary server without interruption.
Critical Notes
- The SCADA project must be identical on both servers.
Even a missing tag, screen, or script may cause failover issues. - Port numbers must match on both servers.
- A dedicated network path (direct cable or separate switch) is recommended for the heartbeat connection.
- The redundancy feature requires a separate license for each server.