Local Client Fallback

Ignition Clients are fully dependent on being able to communicate with a Gateway. If Gateway communication is lost, the Client suspends operation while it attempts to reconnect with the Gateway. This can be a problem when you need the Client to monitor critical operations on a plant floor.

Ignition provides a local Vision client fallback mechanism that lets you use a Gateway running on the machine where the client is running. In normal operation, your Client can connect to a central Gateway located somewhere on the network. The central Gateway would be responsible for all data aggregation, such as storing historical data in a database. But if communication to the central Gateway is lost, the Client can automatically retarget to a project that you specify in the local Gateway. This project should contain the minimal realtime information that you need to keep your operation running.

note

In order to use local client fallback, port 6501 must be open on the local machine.

Enable Fallback

To enable local Vision client fallback, do the following steps:

1. Go to Config > System > Gateway Settings in the local Gateway.

2. Scroll down to the Local Vision Client Fallback section and select Enable Local Fallback.

3. Enter the name of the Fallback Project.

   note

   The selected project must be published in the local Gateway, and it must have at least one main window.

4. Optionally, you can change the Seconds Before Failover setting to a value other than 60 seconds. This setting controls the number of seconds to wait before fallback automatically starts. During comm failure, you can also click a button to load the local fallback project immediately.

   

When local Vision client fallback is enabled, the Client attempts to open port 6501 on the local machine. If the port can be opened successfully, the Client reads fallback settings from the local Gateway and shows a Fallback Project button on the bottom of the Gateway Connection Lost window. You can click this button at any time to load the fallback project, or simply wait for the fallback project to automatically load. You may want to set the local Client to automatically log in to avoid typing in a username and password when the Client loads. This can be set in the Login section of the project's properties.

Test Local Fallback

Testing local Vision client fallback is highly recommended before you start to depend on it in a production setting. The easiest way to test fallback is to simply unplug the network cable to the Client machine, or disable the network card on the machine. If the Fallback Project button is not visible on the Gateway Connection Lost window, check your local Gateway console and verify that the message "Started Fallback Socket on port 6501" is present in the console. Any other error message related to the Fallback Socket Controller indicates that some other problem has occurred (most likely the port cannot be reserved) and local fallback is not available to Clients.

Automatically Transfer Back

Local Vision Client Fallback will not automatically transfer back to the main Gateway when it is running again, as simplicity was key in this system. You can, however, provide your own solution to automatically switch back. One example is to add a retarget script to your Timer Client Event Scripts to silently try to reconnect.

# add this to a Client Timer Script running every 30 seconds
# change the ipaddress and project names to match your system
  
# allow the main copy of Ignition 10 seconds to give a response
status = system.util.getGatewayStatus("ipaddress:8088/main", 10000)
# if it's running again, retarget
if status == "RUNNING":
    system.util.retarget("my_project", "ipaddress:8088")

Fallback Cache Authentication

Fallback Cache Authentication is a User Source created specifically for use with Local Client Fallback, allowing users to cache credentials from a remote user source. See the Fallback Cache Authentication page for more details.