Home » Troubleshooting a Notifier NFS-640 Dialer “No UDACT” Error

Troubleshooting a Notifier NFS-640 Dialer “No UDACT” Error

by kevinfiske.com

As fire alarm technicians, we sometimes encounter puzzling error messages on control panels. One such issue is the “No UDACT” error on Notifier’s NFS-640 dialer with a UDACT (1) attached. This error indicates the panel isn’t recognizing the UDACT communicator, preventing it from sending signals to the central monitoring station.

This blog post will guide you through troubleshooting steps to resolve this error and get your communication back online.

Understanding the “No UDACT” Error:

The “No UDACT” message signifies a communication breakdown between the NFS-640 dialer panel and the UDACT (1) communicator. This can happen due to various reasons, ranging from loose connections to programming inconsistencies.

Troubleshooting Steps:

Here’s a step-by-step approach to diagnose and fix the “No UDACT” error:

  1. Basic Checks:
    • Physical Connections: Confirm that all cables between the UDACT (1) and the NFS-640 are securely fastened and free of damage.
    • Power Supply: Ensure both devices are receiving adequate power. Check for any loose connections or faulty power supplies.
  2. UDACT (1) and NFS-640 Programming:
    • UDACT Settings: Meticulously examine the UDACT (1) programming. Verify it’s set for the correct communication protocol and address format required by the central station. Refer to the UDACT manual for specific programming instructions.
    • NFS-640 Dialer Settings: Double-check the dialer settings on the NFS-640. Ensure the UDACT (1) is properly configured in the panel’s communication setup. Refer to the NFS-640 manual for programming instructions.
    • Slot 56: One user pointed out that Slot 56 in NFS-640 programming can affect UDACT communication. Make sure Slot 56 is programmed for “2” (Receive) or “4” (Transmit/Receive). Consult the NFS-640 manual for details on Slot 56 programming.
  3. Advanced Troubleshooting:
    • Soft Reboot: If the basic checks fail, try a soft reboot of the NFS-640 panel. Power down the panel for a few minutes and then power it back on. This can sometimes clear minor glitches.


Remember, these are general troubleshooting steps. It’s always recommended to consult a qualified fire alarm technician for any procedures involving the fire alarm system.

By following these steps, you should be able to effectively troubleshoot the “No UDACT” error on your Notifier NFS-640 dialer and restore communication with the central monitoring station. ( For Further Information Contact Me )

Also Read : Simplex 4010 Fire Alarm Control Panel: Addressing “Event Queue Overflow” Trouble

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