I can't give you positive confirmation based on my knowledge of the French term, but from technical logic, I would think it probably means a 'rolling' delay — i.e. it starts again at the next trigger, regardless of how much of the previos delay was left to run. E.g.:

Triggered delay to run for 5 mins, after 2 mins triggered again, so new 5 min delay starts...

A bit like the same idea as a 'rolling average' (though not EXACTLY!)

I ahve come across the French term 'rotative' used in a meaning not dissimilar to this, albeit in a different context.

I'm also inclined to agree with you — only minutes really makes sense to me here and I think they are being dangerously imprecise to use 'ms' as the abbrveiation for it — but do note the French love of using 'kms' for kilomètres...

'the alarm sounds at regular intervals and can be programmed to go off every 5, 10, 15 miliseconds (up to 2000ms)'
Assume it is milliseconds and not minutes as an alarm going off every 2000 minutes wouldn't be very effective! hope this helps! paul