We currently have ignition gateway setup in the cloud, all sites are connected to the gateway via MQTT, and the site clients are running on perspective&vision.
If the site lost 4G signal connection to the gateway, the operator can switch over to local HMI either on vision/perspective.
It's not automatic changeover, the operator needs to switch over manually, also there's duplicated work required for programming local screens, mainly remapping all tags to the local tags, instead of MQTT tags.
Is there any better topology than the current setup? I would like to remote the duplicated engineering hours on the graphic development.
For automatic fall back, you can configure the local gateway to be a fall back in the web page config for Vision. It'll then automatically switch over to the local client if it drops connection. Perspective Workstation can be configured to fall back in its config as well
For tags, you could script converting the tags from mqtt to another driver, as well as creating the local device connection. You may even be able to use the main gateway as your master and have the scripts automatically run if the gateway hostnames is one of your local hmis. Could be dangerous if it converts the main gateway's tags... There are some other potential gotchas as well
I will have a try of the auto fallback function.
Yes, currently all tags are configured with indirect address to a "tag provider" tag, which allows me to change them quickly. also the tag structure are configured the same under tag browser. But still, it involves extra engineer hours. I was looking for some sort of Ignition software platform side of redundancy function which can unify the local and remote configuration into one set, but maybe this is the only way to go.
You can use the EAM module to synchronise gateways (tags, graphics, etc) if this is what you're after?