How to Collect Alarms from Your Hochiki FireNET Plus FACP

By Andrew Erickson

January 21, 2023

When you've been in the fire alarms business as long as we have, you learn all of the major players. Hochiki is absolutely one of the significant names in fire panels.

We've worked to engineer support for the Hochiki fire panels you may have installed in your system. That's true of both our Muxpad device (which collects printer-port alarm data from Hochiki fire panels) and our Prism LX (which can be your central collection and alarm display server).

Hochiki FACP sending RS-485 text alarm data to Prism LX via Muxpad

This diagram demonstrates how a mediation device like a Muxpad can take advantage of RS-485 ports designed for LCD annunciators to collect alarm data, process it, and send it to your central monitoring master station (Prism LX in this example diagram).

Our industry experience means that it's not too difficult for us to provide a high-level summary of related equipment like that made by Hochiki. Whether you need Digitize equipment or not, you're welcome to use the following information as part of your project:

Overview of Hochiki FireNET Plus FACP

The Hochiki FireNET Plus Integrated Network System is a fire alarm control and communication system. This FACP (Fire Alarm Control Panel) includes many functions, such as:

  • 120VAC and 240VAC options
  • Various color options
  • A single Signaling Line Circuit loop (SLC loop). That means you can handle up to 127 addressable analog points (sensors/modules).
  • An LCD display supporting 4 lines of text
  • 4A of power
  • 2.3A for each of 2 "Class B notification appliance circuits"
  • 500 zones for grouping
  • Analog smoke detector support
  • Auto-learning mode to accelerate your initial setup
  • Integrated help on the LCD screen

Supported Devices & Equipment

The user manual for the Hochiki FireNET Plus mentions several types of accessories that may be integrated into your overall system, including:

  • Network interfaces
  • SLC loop expanders
  • I/O boards
  • Serial LCD annunciators
  • "Graphix" LED annunciators
  • Analog smoke/heat sensors (photoelectric, ionization, heat, fixed temp, heat rate of rise, multi-criteria, duct smoke, with output relay)
  • "Bases" (to fine-tune sensor positioning)
  • Remote test stations
  • Input modules (standard or mini)
  • Output modules (Class A Supervised)
  • Relay output modules
  • Sounder bases (standard or low-frequency)
  • Pull stations
  • Programmer devices
  • Battery enclosures (33AH or smaller batteries)
  • Flush-mount system

Compatible BOSCH devices

There are also BOSCH-manufactured accessories that match many of the categories listed above. Among the various smoke sensors and analog sensors and relay modules, I did notice a BOSCH "Short Circuit Isolator Module" that didn't appear in the above list.

Compatible devices from Silent Knight, Fike, and other manufacturers

Hochiki's user manual for the FireNET Plus FACP lists many accessories of similar type to those mentioned above for several other manufacturers, including:

  • Silent Knight
  • Fike
  • VES (including a variety of accessories like "Fast Response Contact Module" and "Remote Test Station for Duct Detectors" that I didn't see listed anywhere else)

How do you read/decode a Hochiki fire panel part number?

Like many other manufacturers, Hochiki part numbers have an orderly way of encoding a product's properties in its part number.

In the following order, you'll find:

  • Product style (ex. "FNP" for this fire panel)
  • Number of loops
  • Device range
  • Language (programming and documentation, etc.)
  • Feature code (whether network card or dialer)
  • Expandability (either 0 or 1)
  • Panel color and style (a letter code)

Fire alarm systems and devices have limitations

Here we get to where the lawyers probably stepped in during the writing process to limit exposure to liability. As a result, this section of the manual references fire codes (ex. NFPA 72) that must be followed to give the system the best chance of functioning properly in an actual emergency.

There's also this fairly discouraging little factoid from the US Government:

A study by the Federal Emergency Management Agency (an agency of the United States government) indicated that smoke detectors may not go off or give early warning in as many as 35% of all fires.

This is followed by a solid 2 pages of specific instances where a fire alarm may not be effective, whether due to high winds, technical malfunction, or "deep sleepers." Yikes.

I don't take any issue with what Hochiki has done here, of course. I expect to see very similar language in any manual I crack open.

Perhaps warnings like these are simply a reminder of 2 important facts:

  • Fire alarm monitoring systems are inherently interwoven with the underlying NFPA-dictated legal requirements, and
  • You must do everything you can to minimize the risk of fire that exists by properly monitoring your Hochiki fire panel.

So, how do you actually go about collecting and reporting alarm signals from this FACP?

How do you remotely monitor your Hochiki FireNET Plus?

With some of the basic device information out of the way, how would you go about monitoring a fire panel like this to both comply with code (your minimum legal duty) and actually deliver more than just the baseline public safety?

There are many chapters in the user manual for this FACP, including chapters covering:

  • Physical install
  • Power supply
  • Expander boards (we'll use this one in a moment)
  • SLC device installation (these are the individual things we will collect with the Hochiki panel)
  • Network connections
  • Basic front panel operations and programming (necessary to set up remote monitoring during installation)
  • Testing and troubleshooting

Now, let's look at specific methods:

Monitoring your Hochiki via FN-4127-IO expander board(s)

Hochiki built the FireNET Plus panel to support up to 32 FN-4127-IO expansion boards (just one board is typical) to latch relay closures to report up to 16 alarms per board. These can be picked up by something like a Muxpad device and forwarded to your central alarm monitoring center.

See the "Configuring Outputs" section of your Hochiki user manual to verify all diodes and voltages are properly set. Output channels can actually by damaged by an incorrect installation.

We design and manufacture the Muxpad at Digitize, but we don't control the design of Hochiki equipment. Be sure to follow all manufacturer documentation.

Monitoring your Hochiki via the RS-485 port originally built for the FN-LCD-S Serial LCD Annunciator

Although the Muxpad is capable of receiving contact closure outputs, it can also receive and interpret text-based (ASCII) alarms from a printer or LCD port.

The FN-LCD-S Serial LCD Annunciator is an accessory that you may choose to add to your Hochiki to give it a redundant display for those far away from the actual FACP.

Alternatively, you can use the RS-485 port and directly connect to a Muxpad. The Muxpad will receive and interpret the text, as if it were an LCD Annunciator. Instead of displaying alarm info on a screen, the Muxpad will then forward it to your central fire alarm monitoring facility.

Contact Digitize to discuss your project

It's one thing to learn the absolute basics about alarm monitoring on my blog here. It's quite another to learn about the finer points about a specific application like monitoring the Hochiki FireNET Plus discussed here.

At this point, your best (and fastest, and easiest) move is to just speak with an engineer at Digitize. We've done this kind of thing for decades, and we can help you finish your project as quickly and correctly as possible.

Call Digitize at 1-800-523-7232 or email

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...Read More