> 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-product-adv.md). # F Series Fence Controllers product advisory — March 2023 Review the original F Series optical tamper issue and interim mitigations. ## What happened **24 March 2023.** Several **F32 Fence Controllers** at customer sites experienced the **optical tamper not functioning correctly**. Investigation showed the **Comms LED on the fence controller PCB interferes with the signal for the optical tamper**, causing it to go in and out of tamper alarm repeatedly. The cause is an alternative LED with a higher degree of brightness, and the location of the LED on the PCB. ## Status at the time of this advisory A firmware update adapting the Comms LED behaviour, to eliminate the interference and reflection in the optical tamper sensor, was in development. It is backward compatible with currently supported versions of Command Centre. ## Short-term options until the firmware was available * **Where the fence controller tamper is required:** place bluetack, foam tape or similar over the Comms LED on the PCB to block the emitted light. The Comms LED is not visible when the cover is on, so covering it has no impact on product performance and is easily removed if a technician needs to view the LED when diagnosing a comms fault. * **Where the fence controller is in a tamper-protected field cabinet:** if using Command Centre, disable the tamper on the fence controller properties (Status and Overrides). If operating in stand-alone mode, disable the optical tamper by switching **dipswitch 2** to the disabled position. It is enabled by default. All stock was unblocked globally. ## Affected part numbers * G21920 / G21921 / G21922 (F31 / CAN / APAVE) * G21930 / G21931 / G21932 (F41 / CAN / APAVE) * G21940 / G21941 / G21942 (F32 / CAN / APAVE) * G21950 / G21951 / G21952 (F42 / CAN / APAVE) Contact: Dave Solly, Value Owner - Access, Detection & Deterrence, . *** 🔗 **Related** * [F Series Fence Controllers Product Advisory Update - June 2023](/knowledge-hub/products/product-advisories/historical-notices/f-series-fence-controllers-advisory-up.md). The firmware fix that closes this advisory. * [F-Series Fence Controllers - Channel - Feb 2020](/knowledge-hub/products/product-advisories/historical-notices/f-series-fence-controllers-channel-feb.md). The earlier lightning diverter advisory on the same 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-product-adv.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.