Determine is OPC is using failover source

Ignition
1

Hello all,

We have a redundant gateway connected on two IGS server. One IGS is the primary OPC server and the other one is a failover.

How to know if Ignition is using the primary IGS of the failover one? A tga somewhere that I can historize?

Thanks,

2

You can grab that information through the System/Gateway/Redundancy tags.

https://docs.inductiveautomation.com/display/DOC80/System+Tags

3

I would like to do that, but it’s seems there is not bit indicating if the opc connection is using or not the failover source.,

4

I don’t think this is possible right now unless you can create a tag in the primary and failover server that has a different value and monitor it.

Eventually we’re going to do some work on the failover functionality, including status, the ability to switch back to primary, and some kind of “warm” mode.

5

Thank you Kevin.

How is actually managed the switch back to primary?
I’d like to have more information about the failover management? Is there any documentation about it?

Thanks.

6

It’s not actually managed at all. It will stick to whatever server it can connect to.

The original implementation of this failover many years ago was just a quick “hack”. The idea was that since the servers have to be identical for failover to work it doesn’t actually matter what server you’re connected to.

7

Ok I understand.

So it mean if OPC1 fall down, Ignition will connect to OPC2. Then if OPC1 come back alive, Ignition if stay connected to OPC2 until OPC2 fall down.

Am I correct?

8

Yes.

9

Kevin,
has there been any progress in failover functionality since this post?

10

Not really, no.

Eventually we're going to do a new OPC UA connection implementation that understands OPC UA Non-transparent Redundancy, which means it will handle any number of servers in a server set as well as the rules for determining which server has priority as the spec describes it.

This janky and naive failover implementation will essentially disappear from the foreground, probably hanging around on upgrades if people have it configured, but not available for new connections.

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11

awesome, thank you. any idea on a timeline?

12

It would be sometime after 8.3.0 for sure. Nothing more solid than that.

1 Like