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Multi-Building Alarm Echo to a Single Fire Alarm Control Panel (FACP)

By Andrew Erickson

September 20, 2021


I got a call recently about a six-building complex that, due to local fire ordinance, requires that the fire detection system in each building be linked back to just one conventional fire alarm control panel (FACP) in the central building.

This improves overall life safety, as the fire department can report to the central building if a fire occurs, then get faster situational awareness of all buildings. This is a technology requirement that will save lives.

Let's take a look at the setup of monitoring equipment that will do this job...

Project Requirements:

Here's what I reviewed with my client in the intro letter of my sales proposal:

  1. Contact-closure alarms from 5 other buildings must come back to your main building via LAN/fiber.
  2. About 60 total alarms must be reconstructed at your main building as contact-closures to be compatible with your fire-alarm panel.
  3. If possible, fiber-based devices make things easier for you.

Step 1: Collect Alarms from Each Remote Building

Before your can "move" a contact-closure alarm from one building to another, you first need to collect it. That's the job of any traditional alarm remote (RTU), as long it can forward alarms over LAN (or similar).

NetGuardian M16 G2 and a TrapRelay RTU connected to FACP
In this solution, a NetGuardian M16 G2 in each of 5 buildings is used to reconstitute discrete alarms as contact closures for a Fire Alarm Control Panel (FACP)

Be sure that any RTU you choose is able to handle the transport that's most convenient for your site. As an example, my client in this case was interested in fiber (SFP modules) if possible for added convenience. I quoted this as an option. The price was a bit higher, but it can be worth it if you're eliminating other purchasing of converter devices.

For my client, I quoted two different builds of the NetGuardian M16 G2. One has an additional internal circuit board that adds dual SFP fiber sockets. The SFP modules themselves will be chosen by the client for this project, which involves very short fiber runs (mostly less than 1 km). If needed, I could quote them from our product database, but I don't expect that this will be necessary here.

As I said in my proposal letter: "The system and options I've quoted you here collects up to 16 discrete alarms per building with a NetGuardian M16 G2 at each. If you choose 'Option B', you will maximize fiber connectivity as much as possible. The NetGuardian M16 G2 has an SFP fiber option. To get us started, I am assuming that you have your own SFP modules to insert into the NetGuardians' sockets. If needed, I can quote you some SFPs that we stock."

Step 2: Reconstruct Alarms at the Central FACP Building

Once contact closures have been captured by a network-enabled device of some kind, they can be sent to the central building. But then what happens?

You next need to reconstruct the alarm states as contact closures for your non-addressable fire alarm control panel (FACP).

To do this, you use a device like a DPS Telecom TrapRelay. This inverts the normal RTU formula. Instead of contact closures driving SNMP traps, SNMP traps drive contact closures. Notice the interplay when you have both NetGuardian RTUs and a TrapRelay device in the same network:

The TrapRelay "Echoes" (matches) the state of up to 64 total NetGuardian alarms at your main building's fire alarm panel. This effectively reconstitutes the state of a contact closure in another building into your main building, where it can be picked up by your fire alarm panel as required.

More Detail About the TrapRelay 64 Device

The TrapRelay 64 was designed for those who need a high volume of control relays that could process inbound SNMP traps to operate relay outputs. It wasn't really designed with fire alarm system call points in mind, but it has turned out to be a state-of-the-art solution for this problem.

With the 64 control relays, you'll be able to remotely control any device that you normally operate with a button or a switch. The relays will release or latch a contact closure based on the commands it receives.

Relays are perfect for turning on small devices, opening doors, and interfacing to legacy alarm systems like FACP.

The TrapRelay 64 is operated in Granular Mode, which allows the user to configure each relay to operate or release based on the enterprise, generic trap, and specific-trap information of SNMP. This mode is very general and can be used with most devices.

This device also features the ability to map the same trap to different relays based on the IP address of the device from which it originated. Available in Dual +24V, Dual 110AC (Via Power Adapter) and Dual -48V Power.

The TrapRelay 64 is capable of receiving SNMP Traps Commands (SNMP v1) to open, close, or momentarily toggle any of its 64 relays.

Relays are factory-shunted to Normally Open and are software-selectable for either Normally Open or Normally Closed contact utilization.

Employs screw lug pluggable connections to securely and conveniently terminate the relay outputs directly.

Features: 64 relays, 10BaseT LAN, -24VDC Dual Power input with Fuse alarm indicator, SNMP Capable, Screw Lug Locking RIA power connector, Web-browser based monitoring & provisioning, 32 LED's on the front indicate the relay energized state (Cycles between Solid Red for 1-32 Relays and flashing Red for 33-64 Relays), 2 RU, 19-inch rack mountable, RS232 DB9 craft port, white, RoHS.

More Detail About the NetGuardian M16 Device

The NetGuardian M16 G2 is a small to mid-size IP-based RTU that forms the foundation of many successful alarm strategies. It will be responsible for collecting critical site information and reporting it to either a T/Mon or SNMP manager.

The NetGuardian M16 G2 is a RoHS alarm remote that provides 16 discrete alarm inputs, 6 analog inputs, 2 or 18 control relays, all in a 1 rack unit of space.

The discrete inputs of the NetGuardian M16 G2 monitor items such as door alarms, equipment alarms and other ON/OFF events. The discrete alarms are "software reversible" to support both N/O and N/C alarm wiring. Qualification times may be set for on-set and on-clear.

The analog alarms are used for measuring such critical events as temperature and voltage (+/- 92VDC or 4-20mA). Each of the analog alarms can be assigned qualification times so that transient and nuisance alarms can be filtered out. 6 analogs - 2 power and 4 general purpose each with analog support and four programmable threshold alarms. Shunts to go from voltage to current (adds 250 ohms resistor).

The control relays are a convenient and time efficient way of remotely switching equipment in the field.

What do you need DPS to build for you?

This is just one example of a solution I put together for a DPS client. What is it that you need DPS to build for you?

Give me a call at 559-454-1600 and tell me - or send me an email at sales@dpstele.com

Andrew Erickson

Andrew Erickson

Andrew Erickson is an Application Engineer at DPS Telecom, a manufacturer of semi-custom remote alarm monitoring systems based in Fresno, California. Andrew brings more than 17 years of experience building site monitoring solutions, developing intuitive user interfaces and documentation, and opt...