According to the vendors information there was no way to trigger the Nissin Di622 remote in any other way than with another flash or the pop-up flash of your camera.
I even saw videos where people would physically modify their Di622 to make radiographic triggering possible.
However, I don’t say that it isn’t possible to do this with another set of triggers. This is just the only one I’ve tested and that worked shot after shot after shot after shot…..
I’m repeating myself.
I hope this helps.