Hey man,
nice work, but switching between manual and auto fire with control signals feels clunky for me. I would much rather prefer turning auto fire on and off with a checkbox in the artillery train gui. Could you add this?

The mod https://mods.factorio.com/mod/ArtillerySwitch/discussion/5ca6c76975e41c000c682e25 adds a GUI button you can toggle for each train by clicking while riding on the train. He hasn't updated and has a bunch of glitches, so I'll look into adding something like that to mine too.

I generally wouldn't mind seeing the checkbox too, but the part that feels clunky to me is the positive & negative aspect of the control signal. It also looks like you programmed it so the state only updates upon entering a station and not a change to the signal state. All-in-all it doesn't seem intuitive to me.

In my opinion, I would ultimately like to see something like this...

Toggle in train menu: Toggles between Normal(Default)/Automatic mode and Manual/Signal mode

In Normal(Default)/Automatic mode it operates like vanilla...auto-fires if the target is in auto-fire range, manual fires otherwise

In Manual/Signal Mode, the default is manual targeting only with auto-firing enable by signal: 0 (off, not present) for manual mode, 1 (or positive) for automatic. Firing mode should update with changes to the signal state without requiring the train to leave and return to the station allowing the state to be changed in real time by the circuit network. It also means that the train will automatically return to manual mode when leaving a station. (A situation I would prefer over a the current toggle so if I'm at an auto-fire station, leave, and stop the train between stations it doesn't start auto-firing.)

Lastly, on a side note, have you put updating your dependencies on your list? I was surprised when it showed up as dependency as it is the first mod I've run into outside Optera's that was using it...I'm assuming you know that Optera has deprecated opteralib and has started using flib instead? From what I've read in the discussions the only reason it was updated this last time was for the people like yourself which were using it as a transition period but there were no plans for further updates.

Firing mode should update with changes to the signal state without requiring the train to leave and return to the station allowing the state to be changed in real time by the circuit network. It also means that the train will automatically return to manual mode when leaving a station. (A situation I would prefer over a the current toggle so if I'm at an auto-fire station, leave, and stop the train between stations it doesn't start auto-firing.)

I second this.
I'm building artillery bridgeheads and I bring turret ammo and oil for flamer turrets in a train that also has artillery wagons. I'd like to be able to toggle the artillery to automatic as soon as the ammo and oil is distributed, but not before. In this way, the artillery only starts shooting when the bridgehead is ready to defend itself. Unfortunately, this isn't possible at the moment, since the artillery on the train doesn't react to the signal change.

Latest release has manual buttons. I'll work on improving the circuit control next.

In Factorio 1.1 they added "relative" GUIs, so it was really easy to add "enable"/"disable" buttons to the side of the Artillery Wagon GUI. My procrastination paid off ;-)

Please give the latest version a test! I think I've added everything that was asked for. Trains will update based on changing circuit signals (after a delay). There's a checkbox to ignore the circuit signals and revert to manual control.

The only question I had is if you open the GUI for one wagon, should the controls affect all the wagons in the train or just the wagon you opened?

Thank you very much for updating!

I'm looking forward to testing your changes today. To answer your question: It's good if it affects all wagons, since I think the most common use case is that players want to keep the train save from attack during unwanted stops or in outposts that are not well defended yet. So if it affected only one wagon, we'd have to repeat the process for each wagon - that could become tiring very quickly.

Okay, now the controls affect the entire train at once.

You can still have just one wagon not respond to the circuit signals if you change its checkbox while it's uncoupled from the rest of the train. I have no idea if that will be a useful feature, or if anyone will want it to be more convenient. I imagined that if you have modded artillery shells installed, you might want to have one loaded with nuclear shells and only target that one manually. But that's not much help since you can't assign artillery remotes to specific turrets/ammo anyways.

Been working on updating mods for 1.1 where the devs have been slower to react so I can actually run my primary save...

I agree re: controlling a whole train vs individual wagons; I'd say control the whole train. Looking forward to trying it out!

I tried it and it works great! Thank you very much for updating ^^