Hochiki FireNET FN4127 Circuit Board Diagram Availability and Wiring Details

User question

Circuit board diagram of Hochiki FN4127

Artificial Intelligence Response

Direct answer to the question

• Hochiki does not publish a component-level circuit board diagram (schematic/PCB artwork) for the FireNET FN‑4127. What is publicly available are the official installation/operation manuals and option‑board datasheets that provide block diagrams, terminal/pinout information, wiring diagrams, ratings, and configuration details. (manualslib.com)
• If you tell me whether you need wiring/terminal details, network/expander connections, or help diagnosing a fault, I can extract the exact pages/specs you need from the manuals and outline safe test steps.

Key points

• Basic panel = 2 SLC loops; expandable to 4 with the FN‑4127‑SLC dual‑loop expander. Each SLC supports 127 addressable devices. (manualslib.com)
• Four onboard NACs; later hardware revisions are rated 2.5 A each; use 10 kΩ EOLR on supervised outputs. (manualslib.com)
• 24 V AUX power output limited to 500 mA. (manualslib.com)
• RS‑485 “I/O Comms” bus supports up to 32 FN‑4127‑IO boards (512 I/O points); network NIC supports up to 64 nodes. (hochikiamerica.com)

Detailed problem analysis

• Why the schematic isn’t available

  • Fire alarm control panels are life‑safety devices certified under UL 864 (in the US); manufacturers typically release only system‑level documentation. The FN‑4127 installation/operation manual gives the functional architecture, wiring and ratings, but not a component‑level schematic. This is intentional for safety, liability, and IP reasons. (manualslib.com)

• What you can get (and use effectively)

  • System/block view: The manual shows how the front annunciator, main control unit, power supply, SLC drivers, NAC outputs, RS‑232, RS‑485 I/O bus, and network connections relate, including front‑panel and internal layout drawings. (manualslib.com)
  • Terminals and ratings:
  • SLC: 2 loops standard; 127 devices per loop; add the dual‑loop expander for 4 loops total. (manualslib.com)
  • NACs: 4 supervised outputs; later panels (≥ Jan 24, 2005; s/n ≥ 411‑00412) are 2.5 A per NAC; earlier hardware is 1.6 A. (manualslib.com)
  • EOL supervision: 10 kΩ, 1/4 W EOL resistor (Hochiki PN 0400‑01046) on supervised outputs/NACs. (manualslib.com)
  • AUX power: 24 VDC, 0.5 A max from the panel. (manualslib.com)
  • Relays: Dedicated Form‑C relays for Fire, Fire 2, Supervisory, Trouble, Auxiliary are shown in the Relay Outputs detail. (manualslib.com)
  • Expansion & networking:
  • FN‑4127‑IO: 16 channels per board, up to 32 boards per panel (512 channels), 4‑wire connection (2 power + 2 data), inputs are opto‑isolated dry‑contact, outputs are open‑collector (100 mA max each). (hochikiamerica.com)
  • FN‑4127‑NIC: RS‑485 networking up to 64 nodes on a FireNET network. (hochikiamerica.com)

• Practical translation if you were expecting a “board diagram”

  • Instead of a PCB schematic, treat the manual’s “Power Supply and Main Control Unit Connections” and “Relay/NAC details” as your wiring/terminal map. Those pages provide connection points, supervision requirements, and current limits you can use for installation, commissioning, and black‑box diagnostics. (manualslib.com)

Current information and trends

• The FN‑4127 documentation set remains the public source of record for wiring and ratings; Hochiki’s site continues to host option‑board information (FN‑4127‑IO, FN‑4127‑NIC). (hochikiamerica.com)
• Hochiki’s newer FireNET L@titude platform and training resources indicate ongoing product evolution; if you are starting a new design, checking current platform documentation and training is advisable. (hochikiamerica.com)

Supporting explanations and details

• NAC supervision and polarity: In standby, NACs present a supervisory voltage across the EOLR; in alarm, the panel drives 24 VDC to power appliances. Matching the EOL value is essential to avoid false “open”/“short” troubles. The manual’s NAC connection detail shows the supervised topology and EOL location. (manualslib.com)
• SLC topology: The manual covers Class B (Style 4) and Class A (Style 6/7) wiring and device counts; stick to the listed cable gauges and distances for compliance and noise immunity. (manualslib.com)
• RS‑485 expansion: Use proper A/B polarity, end‑of‑line termination as specified, unique addresses per I/O board (1–32), and observe voltage‑drop limits when powering remote I/O. (hochikiamerica.com)

Ethical and legal aspects

• UL 864 listing and NFPA 72 compliance require that field repairs not alter certified assemblies. Component‑level repair of a FACP can void the listing; the accepted practice is board/module replacement via the OEM or an authorized depot. Use only documented wiring, programming, and accessories. (manualslib.com)

Practical guidelines

• If you need wiring/terminal diagrams now:
  • Power, battery, AUX, NACs, relays, remote inputs, RS‑232 printer/PC, RS‑485 I/O bus, and network connections are laid out in Section 3 of the installation manual; I can summarize any of those with terminal designations on request. (manualslib.com)
• For expansion:
  • Use FN‑4127‑SLC for two additional SLC loops, FN‑4127‑IO for extra I/O, and FN‑4127‑NIC for networking; follow the addressing/termination rules. (manualslib.com)
• Diagnostics without a schematic (black‑box):
  • Ground fault: Remove field wiring incrementally; if the ground trouble persists with only AC/battery connected, suspect internal surge‑protection or wiring to chassis and replace the board.
  • SLC issues: With field wiring removed, verify loop voltage is within the expected range and communication recovers during auto‑learn; otherwise the loop driver or expander is suspect.
  • NAC issues: Verify correct 10 kΩ EOLR and current draw; compare standby supervision vs alarm voltage. The manual’s “Notification Appliance Circuit Connection Detail” is your reference. (manualslib.com)

Possible disclaimers or additional notes

• Some ratings changed across hardware revisions (e.g., NAC current rating). Always verify the panel’s date/serial and use the matching manual notes before committing to a design or repair. (manualslib.com)
• Third‑party websites mirror manuals; when possible, favor the most recent issue from Hochiki or a reputable archive and cross‑check version numbers.

Suggestions for further research

• Provide the panel’s exact model, firmware, and the symptom or the specific connection you’re targeting; I can quote the exact manual page(s) and produce a concise connection map for your case. (manualslib.com)
• If you are evaluating upgrades or new installations, review the current FireNET L@titude documentation and training availability. (hochikiamerica.com)

Brief summary

• A component‑level circuit board diagram for the FN‑4127 is not publicly released. Use the official installation/operation manual and option‑board datasheets for block‑level architecture, terminal maps, wiring, and ratings—these are sufficient for compliant installation, commissioning, and most diagnostics. If you specify what you need (wiring vs. troubleshooting), I will extract and tailor the details immediately. (manualslib.com)

Would you like a one‑page wiring/terminal cheat‑sheet for the FN‑4127 (AC, battery, NACs with 10 kΩ EOL, AUX, relays, RS‑232, RS‑485 I/O, and network), or are you diagnosing a specific fault?

Disclaimer: The responses provided by artificial intelligence (language model) may be inaccurate and misleading. Elektroda is not responsible for the accuracy, reliability, or completeness of the presented information. All responses should be verified by the user.