So far I have successfully been using 2 RasPi’s incl. several bindings on my 2 RasPi’s:
OH2: Rel. 2.5
OH3: Rel. 3.4
OH2 includes the PiFace-daughterboard (-> Garage-door) that requires the legacy 1.x binding: Piface - Bindings | openHAB
On OH3 (primary OH-controller) I was able to access the Piface-Items through the Remote openHAB binding in order to control the garage door.
I’m trying to replace OH3 through OH4 (new installation, openHABian, Rel. 4.0.4 Stable).
Unfortunately I can’t see (link) the PifaceItems on OH4 (through the openHAB binding).
Hence my questions:
Q1: Could it be, that I can’t bridge from OH4 to OH2 for 1.x bindings anymore?
Q2: If OH4 should still support 1.x bindings over openHAB-binding: Any idea why I can’t see the PiFace-items on OH2?
No, the Remote openHAB binding still works in OH 4 and the way that it works hasn’t changed (to my knowledge). This should work.
Not with the information provided. Is the binding installed? Is the Bridge Thing created? Is the bridge showing as ONLINE? Do you have the Things representing the Items in the OH 2 instance? Errors in the logs?
Thank you for your support! 
I’m glad to know that OH4 should still support the Remote openHAB binding as in the past.
Therefore it must be something else.
Here are the answers to your questions:
Q 1: Is the binding installed?
A 1: Yes (OH2):
bundle:list -s | grep piface
270 │ Active │ 80 │ 1.14.0 │ org.openhab.binding.piface
And on OH2 everything works as expected through the Basic UI:
Q2: Is the Bridge Thing created?
Q3: Is the bridge showing as ONLINE?
A2 and A3: Yes and Yes (OH4):
And openHAB2remote is working perfectly for another Thing.
Q4: Do you have the Things representing the Items in the OH 2 instance?
A5: No. There’s no Piface-Thing listed on OH2, even though that the binding is also visible as installed PaperUI:
However its’ not listed under “Bindings” (?):
Q5: Errors in the logs?
A5: On OH2: No. This is what I’m getting after a reboot (related to PiFace). No other errors:
2023-12-01 11:58:02.846 [vent.ItemStateChangedEvent] - PiFaceSwitch0 changed from NULL to OFF
2023-12-01 11:58:02.848 [vent.ItemStateChangedEvent] - PiFaceSwitch1 changed from NULL to OFF
2023-12-01 11:58:02.858 [vent.ItemStateChangedEvent] - PiFaceSwitch2 changed from NULL to OFF
2023-12-01 11:58:02.860 [vent.ItemStateChangedEvent] - PiFaceSwitch3 changed from NULL to OFF
2023-12-01 11:58:02.867 [vent.ItemStateChangedEvent] - PiFaceSwitch4 changed from NULL to OFF
2023-12-01 11:58:02.870 [vent.ItemStateChangedEvent] - PiFaceSwitch5 changed from NULL to OFF
2023-12-01 11:58:02.874 [vent.ItemStateChangedEvent] - PiFaceSwitch6 changed from NULL to OFF
2023-12-01 11:58:02.876 [vent.ItemStateChangedEvent] - PiFaceSwitch7 changed from NULL to OFF
2023-12-01 11:58:02.881 [vent.ItemStateChangedEvent] - PiFaceContact0 changed from NULL to OPEN
2023-12-01 11:58:02.883 [vent.ItemStateChangedEvent] - PiFaceContact1 changed from NULL to OPEN
2023-12-01 11:58:02.885 [vent.ItemStateChangedEvent] - PiFaceContact2 changed from NULL to CLOSED
2023-12-01 11:58:02.886 [vent.ItemStateChangedEvent] - PiFaceContact3 changed from NULL to OPEN
2023-12-01 11:58:02.888 [vent.ItemStateChangedEvent] - PiFaceContact4 changed from NULL to OPEN
2023-12-01 11:58:02.889 [vent.ItemStateChangedEvent] - PiFaceContact5 changed from NULL to OPEN
2023-12-01 11:58:02.891 [vent.ItemStateChangedEvent] - PiFaceContact6 changed from NULL to OPEN
2023-12-01 11:58:02.892 [vent.ItemStateChangedEvent] - PiFaceContact7 changed from NULL to OPEN
A5 on OH3: No. There aren’t any Piface related log-entries at all.
I’m referring to the Remote openHAB binding, not the Piface binding.
There is some confusion here. I don’t care about the Piface binding at all. I assume that works and is fine. Since it’s a 1.x binding it won’t have Things anyway.
I only care about the Remote openHAB Binding on OH 4. That’s the only thing that matters here.
So for this question, on OH 4, do you have Things which correspond to the Items on OH 2 you want to control? The way the Remote openHAB binding works is it connects to the remote OH instance (in this case OH 2) and it is supposed to discover and create Things on the OH 4 instance that represent the Items on the OH 2 instance. These are then linked to Items in the OH 4 instance so that updates made on the OH 2 instance get sent to OH 4 to update that Item and updates commands on the OH 4 instance get sent to the OH 2 Items.
There wouldn’t be. There would only be Remote openHAB entries and even then only if the Things are discovered and configured correctly and perhaps even then only if the binding is put into debug level logging.
What is the most important is the thing representing the remote OH2 server. This thing will expose each remote item as a channel.
Discovering of remote things is more an advanced feature, not required by everybody.
Thank you very much!
Since I ran into several issues after switching to OH4 (new installation), I decided to restore my old setup and to update OH3 to the latest available build OH 3.4.5. This allowed me to even get Netatmo up and running again (which didn’t work for me on OH4).
So for the time being, I will stick to my “legacy” OH 2.5 and OH 3.4.5 setup and will avoid any kind of upgrades. I might consider replacing all my “special” things such as PiFace (Garage) and Domino Swiss (shutters) in a few years. But so far I’m absolutely happy with Basic UI (watch-access), several automation-rules and piVCCU3 (Homematic) running side by side with OH 3.4.5.
So the best for me right now is: “Never touch a running system 
”