Define whether a Listen Port can be Shared

Advanced drivers have channels that support the Listen Port feature, which allows network-connected outstations to initiate a connection to the server. The Listen Port settings in the Channel configuration allow you to define which port is used as the Listen Port (the Listen Port is the port on the ClearSCADA server that is used when an outstation on the channel attempts to initiate a connection).

By default, every channel that uses the Listen Port feature has to be configured to use a different Listen Port on the server—they cannot use the same port number. While this is fine for many systems, in some situations a Listen Port needs to be shared, for example, some devices have to use a fixed port number and so can only be set to use a Listen Port that has a specific port number. If there are multiple devices of the same type in use on the network, this can cause problems as the devices need to use the same Listen Port number. To help avoid this problem, ClearSCADA includes an Allow Channels On a Driver to Share the Same Listen Port feature.

When the Allow Channels On a Driver to Share the Same Listen Port feature is enabled, any outstation in the system can initiate a connection using a single port number. The channel that has the port number (used by the outstation) configured as its Listen Port will automatically check to see if the outstation is active on the channel. If the outstation is active, the channel will be used for the connection; if it is active on another channel, the connection will be automatically redirected to the appropriate channel. This means that multiple devices can use the same port number to initiate connections as ClearSCADA can route the connections to the appropriate channels as needed.

If you are working on a newly installed system, we recommend that you enable the Allow Channels On a Driver to Share the Same Listen Port feature. However, if you are working on a system that has been upgraded, you should leave the Allow Channels On a Driver to Share the Same Listen Port feature disabled (so that your upgraded system works in the same way as your old system).

You can enable or disable the Allow Channels On a Driver to Share the Same Listen Port feature in the Channels settings on the Server Configuration Tool:

1. Access the ClearSCADA Server Configuration Tool (see Accessing the ClearSCADA Server Configuration Tool).
2. Expand the Global Parameters branch of the tree structure.
3. Select Channels to display the Channels section.
4. In the Network section, select or clear the Allow Channels on a Driver to Share the Same Listen Port check box to enable or disable the feature respectively.

   If you enable the Allow Channels on a Driver to Share the Same Listen Port feature, any outstation on the system can initiate a connection by using a single port number (the Listen Port number). The channel that is configured to use the matching Listen Port number is either used for the connection or redirects the connection to the appropriate channel. This means that the outstations can use the same port number to connect into the ClearSCADA server.

   If you disable the Allow Channels on a Driver to Share the Same Listen Port feature, each channel will need to define a unique Listen Port, which may mean extra configuration is required at your outstations (and you may have to compromise when using equipment with fixed port numbers for initiating connections).

5. Right-click on the system icon in the tree-structure, and select the Apply Changes option to apply the changes.

When you have finished defining the Allow Channels on a Driver to Share the Same Listen Port setting, you can either configure other Channels settings. For more information, see the topics that are listed in the gray footer section at the bottom of this topic. Select the relevant entry to display the topic that you require.

Or:

Continue with the server configuration. If you are unfamiliar with the server configuration process, we recommend that you proceed to learn about Driver Settings.