Providing redundant communication by a backup connection

It may occur that the public communication network is down, or that a modem fails to work properly. To make sure that the communication with your external data source, such as a reference station receiver, is working even after such a breakdown of the main (primary) communication link, you can set up modules receiving data (such as, for example, Router modules) for the use of a second connection, the backup connection.

Typically, you will select a dial-in mode connection as backup connection. Trimble 4D Control Server can activate the backup connection automatically after a pre-defined timeout. When the primary connection is again working correctly, an automated procedure makes sure that this primary connection is reactivated.

Setting up the backup connection for a module

Use the Backup Connection category of the module properties to make the second connection known to Trimble 4D Control Server or to change settings for the backup connection. Do the following:

• Enable the backup functionality by setting the Use backup connection setting to Yes.
• Specify the connection settings (connection type and further settings).
• Specify whether Trimble 4D Control Server shall be able to automatically switch to the backup connection if the main connection fails. If the automatic control is disabled, you can only start or stop the backup connection manually.

Manually starting and stopping the backup connection

To start the data transmission using the backup connection (for example, to test that connection) on demand, right-click the module in the Tree view to open its shortcut menu and select Manually Start Backup Connection. The module's shortcut menu now contains the Manually Stop Backup Connection command.

After the backup connection has started (either forced by timeout of the main connection or by a manual start), you can stop the data transmission by the backup connection and return to the main communication link. To do so, go to the module's shortcut menu and select the Manually Stop Backup Connection command.

Note - After you have manually started or stopped the backup connection, Trimble 4D Control Server will only return to the automatic mode, if you enable the automatic backup connection control.

Automatic control of the backup connection

To enable the automatic control of the backup connection do one of the following:

• Using the module properties, set the Automatic backup connection control property to Yes, then specify the times how long the main connection has to be lost (Switch to backup connection after) or running again (Switch to main connection after), before the connection in use is switched to the other one.
• Using the module's shortcut menu, make sure the Automatic backup connection control command is ticked. If so, the functionality is enabled. If not, select this command to switch to automatic control. Doing so sets the module property Automatic backup connection control to Yes, without changing the specified timeout values.

How does the automatic control work?

If the primary connection stops to continuously transmit data, the module waits for the time defined in the Switch to backup connection after property. Then the module uses the secondary connection.

The module icon indicates that the main connection has been disconnected and the backup connection is working. If alarm jobs have been set up for the case that the module switches to the backup connection or that the backup connection has been lost, then also the Alarm Manager module reacts and issues the specified alarm.

A module continues using its backup communication link until the main connection restarts continuously sending data for the time specified in the Switch to main connection after property or until you stop it using the shortcut menu.

Alarming

With alarming activated, the modules using backup connections can trigger alarms, if they have switched to the backup connection and if the backup connection was lost. Remember, that the Alarm Manager module can also be set up to issue alarms when the alarm condition disappears.