> For the complete documentation index, see [llms.txt](https://help.security.gallagher.com/knowledge-hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.security.gallagher.com/knowledge-hub/products/product-advisories/historical-notices/f-series-fence-controllers-channel-feb.md). # F Series Fence Controllers communications advisory — February 2020 Review the F Series lightning diverter change for affected controller installations. ## What happened Monitored pulse fences have the potential for **coupling between the conductive circuits**, mainly when operating in dual pulse configuration. The coupling effect can be amplified where there is minimal separation between wires or fence structure. Sparking caused by short circuiting or voltage leakage can lead to a high voltage pulse **in excess of 16kV** being received back at the fence controller. Pulses exceeding 16kV result in **arcing from the inside of the fence controller through the internal lightning diverter**. Arcing creates a high-frequency pulse capable of travelling through the components, leading to disruptions and potential damage to the **RS485 communication lines for HBUS and LV synchronisation**. ## What Gallagher did Following investigation and extensive testing, Gallagher determined the **internal lightning diverter should be removed from all future production** of fence controllers. All existing stock in Gallagher warehouses was reworked. **The absence of the internal lightning diverter has no adverse effect on product performance.** ## What to do on existing sites For existing sites experiencing RS485 communications issues (HBUS and/or LV Sync): 1. Check all fence controllers on site to ensure the lightning diverter has been removed. **If it is still installed, remove the lightning diverter as the first step.** 2. Check the RS485 communication ports for potential damage. Fence controllers with a **serial number later than 1823xxxxxx** were manufactured without the lightning diverter, so there is no need to check these on site. A technical guide with R\&D-recommended testing and diverter-removal instructions is available on the support site. > ⚠️ **Note:** the internal lightning diverter is a legacy design from early-generation products. Its removal does **not** impact the lightning resistance of the product, **nor does it replace the need for external lightning protection to be installed**. Contact: Dave Solly, Product Manager - Perimeter Systems, . *** 🔗 **Related** * [F Series Fence Controllers Product Advisory - March 2023](/knowledge-hub/products/product-advisories/historical-notices/f-series-fence-controllers-product-adv.md). The optical tamper and Comms LED issue on the same controller family. * [Product Advisories](/knowledge-hub/products/product-advisories.md). The full register of obsolescence, security, and deprecation notices. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://help.security.gallagher.com/knowledge-hub/products/product-advisories/historical-notices/f-series-fence-controllers-channel-feb.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.