FIBER SENSYS FD322 Installation and operating instructions

AN-SM-038 Rev A 141117 Confidential –Limited Distribution
Application
Note
Using the FD322
as a Cable
Break Sensor

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including photocopy, recording, or any information storage and retrieval system, without
permission in writing from Fiber SenSys, Inc., 2925 NW Aloclek Drive, Suite 120,
Hillsboro, OR 97124 USA.
This application note is provided by Fiber SenSys, Inc. (FSI). While reasonable efforts
have been taken in the preparation of this material to ensure its accuracy, FSI makes no
express or implied warranties of any kind with regard to the documentation provided
herein. FSI reserves the right to revise this publication and to make changes from time to
time in the content hereof without obligation of FSI to notify any person or organization
of such revision or changes.
Fiber Commander™is a trademark of Fiber SenSys, Inc.
Fiber SenSys®and Fiber Defender® are registered trademarks of Fiber SenSys, Inc.
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Fiber SenSys, Inc.
2925 NW Aloclek Dr. Suite 120
Hillsboro, OR 97124
USA
Tel: [phone]
Fax: [phone]
[e-mail]
www.fibersensys.com

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The Fiber Defender®product line offers a diverse range of solutions for a wide scope of security
applications. Our products are trusted to protect military, nuclear, industrial, commercial, and
residential applications. The FD322 combines Fiber SenSys’ legacy of high-security and high-reliability
with simple configuration requirements at a very competitive price.
Typically applications with Fiber SenSys perimeter security products involve detection of intruders that
are trying to climb, cut, or crawl through the fence. In these applications, a fiber-optic cable is attached
to the fence, and an alarm processing unit (APU) is connected to the fiber. The APU launches laser
light into the fiber, and by measuring the transmitted and reflected light, the APU can tell when the
fiber is disturbed by an intruder trying to breach the fence.
In some applications, the APU is tuned to detect when the optical fiber is broken. These applications
arise when the environment has lots of vibration and noise, and valuable hardware cannot be
accessed without breaking the fiber. An example of this is the security of medical devices (see Figure
1). Multi-mode optical cable such as SC-4 is recommended for cable break detection applications.
Figure 1
Medical equipment utilizing radioactive material may be
secured within its area using a cable break detector.

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Another possible application for the FD322 as a cable break detector is to protect solar panels at a
solar farm. Deploying the break detection design involves weaving the fiber loop through the solar
panels. The cable is looped through the panels in a manner that the cable cannot be removed without
being cut. In this type of application, the APU can be tuned so that it will not alarm when the optical
fiber is shaken but will alarm when the fiber is broken.
Figure 2
To configure the FD322 to detect breaks only, first verify that the maximum loss in the fiber is less than
5dB.1
The FD322 APU has a built-in loss calculator that functions as part of the unit’s calibration process.
Using the FD322’s custom Tuning Software to check the loss using the APU, execute the “CALIB”
command within the software’s “Terminal Mode” as follows:
1. Enter Terminal mode and type “CALIB” in all caps, then [Enter]
2. Type “ML” and [Enter]
3. Verify that you are prepared to calibrate the processor
4. Shake the fiber for ten seconds and press the test button located under the LEDs on the
corresponding channel of the unit
5. View and record the measured loss value and ensure it is below 5dB
A more detailed description of the calibration process can be found on the FD322 Field Calibration
Video. Please visit http://www.fibersensys.com/products/product-videos. Note: Product and training
videos are available to registered users. Register at http://fibersensys.com/login-or-register.
1. Typically installations <5km have less than 5dB loss.

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If the optical loss is less than 5dB, connect the two ends of the optical cable to the APU and use the
tuning software to disable both processors. When configured in this manner, the APU will not alarm
when the fiber is shaken. The alarm relay will change states if the fiber is broken, cut, or unplugged. If
the IP port is being used, the processor will output a fault indicator via XML messaging when the cable
is disconnected or cut. Figure 3 below displays a screenshot from the FD322 Tuning Software
reflecting the proper parameters for cable break detector applications; observe that all the detection
related settings are disabled.
Figure 3
The cut and climb settings are disabled, so movement of the cable does not cause an alarm; only
cuts, breaks, or unplugging the connector will cause an alarm with these settings.

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The cable break detector can be implemented utilizing one or both of the APU channels. If only one
channel is used, the other channel is typically “jumpered-out,” which means that a short single-mode
or multi-mode jumper would be used to close the loop of the unused channel; that way, either the Fault
indicator or the Alarm indicator can be used with the functioning channel. Both channels share a
common Fault relay so if one of the two channels was not connected, the Fault relay would
permanently be in a fault state, and a red light would signal a fault on the unused channel. The primary
purpose of “jumpering-out” the unused channel is to satisfy the unused channel and prevent the red
LED from illuminating.
Figure 4
Connect one end of the cable being used to detect
breaks to the output port on FD322; connect the other
end to the input port (on the same side).
High Performance - High Reliability - High Security
Fiber SenSys, Inc.
2925 NW Aloclek Drive, #120
Hillsboro, Oregon 97124, USA
Tel: [phone] •Toll free (US) [phone]
www.fibersensys.com