Siemens Mxl rotating troubles

I have a 8 year old mxl network system, I have 300 smokes in a garage open to outside side air .

Every time it rains for days after troubles for smokes go crazy , it over several loops not the same one .

Hi there!

We have Fire Alarm Techs on this board who will be able to help you with solving your predicament.

I do however have some experience in solving troubles and with smoke detectors.

But while were waiting for them, may I ask what troubles your getting? It sounds like the smoke detectors are the devices going into trouble. Is this correct? And it does this after it rains? Did you check the heads of some of the detectors to see if there was moisture in them? Shorting could cause a trouble.



I have never had contact with a Siemens system, but I do have a few questions that may help others make some sense of this.

Are the smoke detectors photo or ion type?

Does the building hold a high humidity level after a rain?

What troubles are being displayed? Be as specific as possible.

Communication troubles like comm fail or bad reply?

Troubles concerning the detector condition like dirty or out of range?

Most systems using smart smoke sensors can generate many different troubles from the devices.


I’ve been working on MXL systems since 1991. The smokes are probably going into trouble for a few reasons.

A. The humidity range is outside the detectors operating window. I’m pasting info from an FP-11 cut sheet but the temp/humidity range range is typical for all Siemens devices:

The operating temperature range for the FP-11 and FPT-11 detectors is from 32°F (0°C) to 100°F (38°C). The thermal alarm temperature is rate compensated at 135°F (57°C). Use these detectors in environments where the humidity does not exceed 93% (non-condensing).

If the detectors are older or ILI series, you may have more problems with humidity.

B. Condensation is building up inside the conduit and interfering with the SLC causing “device communication error” or “Device detected waveform error” troubles. Or, if the circuits are grounding or have an intermittent short due to water, that could be your problem as well.

C. The detectors could be going bad due to high humidity and being exposed to outside air on a regular basis. Do the swipe terminals on the base or detector head itself show any signs of corrosion?

If you can tell me what the trouble messages are I can try to give you some pointers.

Note that when the panel reaches 300 troubles it will stop beeping and push the oldest event out of the que depending on the firmware revision of the panel and how the programming was setup.

Good evening , thanks for help. I will give set up .

Siemens finished install the panel in 2005 so 11 year old building .it is in on a river and 2 mikes from the Atlantic Ocean.

It’s in a 6 story parking deck open on 2 sides one is facing river , it starts after a heavy rain even though smokes don’t get wet.

Seems to have a little corrosion on contacts , can feel it.

Have some pictures just don’t know how to add

Here’s the image posting instructions: <URL url=" text=“viewtopic.php?f=63&t=7785”>

Or, if you email me the photos I can post them for you. I’ll send you a PM with my email address.

They are FP11 smokes and tri-r modules , pull stations

It’s probably humidity and the corrosion on the contacts that are causing your issues. Only thing I can recommend is trying to clean the terminals short of starting to replace the stuff. Has this been happening for a while or did it start recently?

They would get a few a year , a lot of the wire was nicked during install and shield would ground to pipe .

We try and replace as we fine. But the so many smoke in runaway is new and after a few days of rain here in ft lauderdale

Due to the photo uploading issue, I’m posting these images here on behalf of ‘Oldtimer.’



Is that mold on those detectors? :?

If theres mold, theres definitely moisture.

Can we get some pictures of the contacts too?

That head doesn’t look like it’s sitting in the base.

I used to work for Siemens down there back in the 90’s.

I just noticed that too as well…

That would cause a trouble or if it’s shorted the wrong way that definitely would cause a trouble. I still think the moisture could be playing a part in the issue here.

All the heads couldn’t be put in wrong, right? :stuck_out_tongue:

PE11T detectors have several slots and pins that must be mated to insert the detector head, so they can only be inserted in the correct orientation.

If you try to put them in backwards, the head will not drop into the base until it is rotated to the correct location.

However, the fact that this detector is not seated in the base raises this as a possibility. I can’t make out the text on the base to verify the orientation, but the LED should be opposite of the “Cerberus Pyrotronics” label on the DB-11.

The second picture shows that there are installation and maintenance problems that need to be repaired. The detector should fully seat in the base. If there is a reason it can’t then the base, detector, or both should be replaced. The entire assembly should be securely attached to the box, not be hanging by the wires.If the box is too full of other wire joints add an extension ring. There are NEC cubic inch requirements on box size based on the number and size of the conductors.

Once I had a situation with a panel installed in a small damp basement. Moisture permeated the circuit boards causing stray voltages to appear causing false alarms. When I proved that was the issue the customer and electrical contractor agreed to move the panel to a controlled environment location.

As a test, bring some detectors into a environmentally controlled area to fully dry and coat the circuit board with the appropriate Humiseal product. Then reinstall and watch for troubles on those detectors.

Replace the smoke detectors that are causing the troubles

After that, try re-seating the detector. Maybe the trouble just stems from a dirty detector that isn’t seated properly.

B. Condensation is building up inside the conduit and interfering with the SLC causing “device communication error” or “Device detected waveform error” troubles. Or, if the circuits are grounding or have an intermittent short due to water, that could be your problem as well.

Ive got both messages and a steady yellow Trouble light that will not RESET. is there a way to narrow down which of my detectors is acting up? there are around 20+ in my building all connected to this central system. ive checked and all of them look dry and are reporting correctly (unless I missed something).

should I do a hard (all power to system) reset?

Since you posted this in the Siemens Mxl thread I’m assuming this is a Siemens system of some sort, however the following advice will apply to virtually any fire alarm system.

A trouble cannot be reset. “Trouble” conditions indicate a fault in the system that must be fixed. In a few cases (like Class A wiring issues), after repairs have been made a reset is required for the panel to detect the correction and clear the condition. This will vary by trouble and by brand. My Silent Knight panel does not require a reset to detect Class A fault corrections.

When confronted by a laundry list of troubles on a fire panel don’t immediately jump in and try fixing them. Start by reading the display carefully. Often times things like “missing/INVREP/COMM ERROR” troubles involving multiple modules on a loop can be traced to a failed connection at a single point like water in a junction box or corroded electrical connections at a detector, which will prevent data from passing from the panel to devices further down the line.

Is the system addressable? If so, which module numbers are listed? Are the listed module numbers sequential? (indicative of a single point of failure preventing communication with devices further upstream)

If the system is conventional, which zone card/zones are indicating faults? Are they indicating Open Circuit or Ground Fault?

If you could list some of the specific troubles you’re getting that might help us to help you.

Note if the system is actively protecting life and property in a commercial/public building it may be necessary for a trained technician to perform all service.

After learning that the true nature of this problem came about when the building lost power during an actual power outage/backup system test, I was able to go into the control settings and reset it (after input of code for access). we have no further issues at this point. having the info how and when this happened would have been helpful to start… but it was a good opportunity to check the entire system and look at each individual detector (eye roll)