The Cam's External Alarm input line croaked. Why?

[Fastb]

Update - Problem Solved:

Cockpit error was root cause!
I had received too many alarms, due to a high activity event at my house. So I changed the PERIOD setting so alarms wouldn't occur during the event.
Then I forgot I made the changes.
Then I incorrectly blamed the camera's "IPC External Alarm" input line.

Bottom line:
The alarm input circuitry hasn't croaked!

Closing Thoughts:
It would be nice if there was a Diagnostic Screen to show the states of the alarm input and output.
I'd love a "dashboard" to show in real time the raw state of i/o.
Regardless of config settings like NO, NC, Working Period, Anti-Dither, etc.

Thanks everyone,
Fastb

All,

So I had a Dahua dome mounted outside, with a Bosch Tritech MD detector 6 inches away. (p/n at bottom)
The Bosch was connected to the "Alarm In" line of the camera. Everything was grand. I was pleased with performance.

After several weeks, the camera wouldn't detect the Bosch alarm output. Ie: when Bosch NC signal went from Closed-->Open. I checked, and the Bosch was working. Based on its LEDs, and an ohmmeter.

I pulled the camera and Bosch inside. Long story short, the camera's "Alarm Input" signal line doesn't work. It can't recognize an "open" or "closed" on the cam input lines.

My questions to the experts:
- Is this unusual?
- Any idea what fried the camera's alarm input circuitry?
- Are Dahua's camera alarm inputs overly fragile? Is a zener or capacitor recommended?

Thanks everyone! I will replace the cam, but don't want the next one to die!
Regards, FastB

System details:
- Cat 6 POE cable runs from POE switch in house to cam pole in yard.
- POE splitter used on cam pole (http://www.amazon.com/exec/obidos/ASIN/B0146LFMZG/ref=nosim/ipctk-20)
- POE splitter powers the: camera, the mic, and the Bosch
- Bosch output connected to cam alarm input. Distance ~ 6"
- No lightening recently


Camera - IPC-HDBW4421E-AS
Bosch OD850f1 - Tritech. Motion Detect (PIR) plus microwave.
POE splitter - (http://www.amazon.com/exec/obidos/ASIN/B0146LFMZG/ref=nosim/ipctk-20)
Mic - https://www.amazon.com/exec/obidos/ASIN/B004REA7MG/ref=nosim/ipctk-20