Programming Help!!!

I am latching a output off of a hi alarm. When I get a hi alarm it will latch an output. The output will stay latched up for 15 min and if it is still in alarm it will latch it again for another 15 min and if it is still hi it will latch again for 15 min. My question is if the output is latch three times in a row "Back to Back to Back" I want to fire anoter output or alarm. How can I get the alarm. This is Control logix 5000 ladder.

The easiest is a timer (TON) which is enabled by your output being ON (a NO contact). Set the Preset for a little over 30 minutes (1801000) if you want to alarm at the beginning of the third period or a little less than 45 minutes (2699000) to alarm at near the end of the third period.

But, if this timer resets between the periods then you will have to bridge over the slight amount of time between the sucessive settings of the output. Create a second timer triggered by the output being OFF. Set the preset for just a little more than the time between the settings of the output. Then place a NC of the .DN bit of this timer in parallel with the NO of the output mentioned in the enable of the first timer.

Will that set the alarm if the latch is set true three times lets say in 24 hr period or only if is latched in like a 46 min period?

Try just the single timer first. If it resets between the output coming on twice then you need the second timer. Set it for just a little more than the allowed time between two 'settings' of the output to be considered 'back-to-back' (maybe just one second?). I can't tell what that might be. It won't detect three at widely spaced times unless you set that second timer for a very large amount.

From what I'm reading, you want to activate an alarm ONLY if the latch is set true 3 times in a given period. If that is the case, put a timer preset to the given period of time. The first time the latch activates, latch a bit starting the timer. Also increment a counter each time the latch goes true. Preset the counter for 3 and use the counter done bit to activate the alarm. Reset everything with the timer done bit.