There are basically two methods which ERSA describes in a very long winded way. Where a PAL is on the same frequency as the CTAF it is one second on, one second off. When the PAL is on its own frequency it is normally 3 seconds on and 1 second off.
As I alluded to earlier, what can be really stressful even if you are sure that you are keying the correct tx sequence is that no confirmation message is being transmitted from the unit. Not fun flying to a location in the dark and not knowing if you have lights until you're visual with the field. Leigh Creek has one such unit. The only saving grace being that there is a flashing beacon that is visible for quite a ways out on a clear night. From memory though, the flashing (rotation) interval on the beacon is not as per the published 6 seconds. Might be time for a bit of maintenance of the system out there.