> 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/deployment-resources/install-and-commission/wiring-basics/wiring-inputs.md). # Wiring Inputs [Compliance & Reference](broken://pages/xT7N7IT3BP4gxJvnsCrN) › [Wiring Basics](/knowledge-hub/deployment-resources/install-and-commission/wiring-basics.md) › Wiring Inputs > 📋 **Prerequisites:** Read the [Wiring Primer](/knowledge-hub/deployment-resources/install-and-commission/wiring-basics/wiring-primer.md) first if you are new to voltage, current and resistance. ## This page answers * What counts as an input? * Where should the resistors be installed? * How many states can each resistor configuration detect? * How fast does an input respond, and how long can the cable be? * Can an active device be monitored? The different resistor configurations and locations you can use with Gallagher hardware, and the pros and cons of each. ## What is an input? An input can be anything the system needs to monitor: * PIR (motion detector) * Reed switch * Door position sensor * Heat/fire detector * Duress button * Any other device Gallagher needs to monitor ## Where should the resistors be installed? The best place for the resistors is at the **device being monitored**, as close as possible to the contacts being monitored. The further away they are from the contacts, the easier it is to interfere with the status of the device, and in a security situation that is not advisable. If the resistors were installed at the monitoring device instead, meaning at the Gallagher hardware, it would be trivial for an intruder to bypass the security of the device installed. ## Methods of monitoring input states Gallagher inputs can be configured for multiple methods. | Resistors | States | State list | Notes | | -------------------------- | ------ | -------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **None** | 2 | Closed Circuit (normal), Open Circuit (alarm) | Low security, **not recommended**. If the cable is shorted, deliberately or accidentally, the status reads as closed while the actual state of the input could be anything. | | **One** | 3 | Closed Circuit R1Ω (normal), Open Circuit (alarm), Short Circuit (tamper) | Low security, **not recommended**. If the input is shorted at the device, the input state could be anything. | | **Two (dual end-of-line)** | 4 | Closed Circuit R1Ω (normal), Open Circuit R1+R2Ω (alarm), Short Circuit (tamper), Open Circuit (open) | The **minimum requirement**, and standard with Gallagher on initial configuration (can be changed). | | **Three** | 6 | Closed Circuit R3Ω (normal), Open Circuit R1+R3Ω (alarm), Short Circuit (tamper), Open Circuit (open), Fault, Masked | Only available in versions of **Command Centre 8.10 and above**. | ![No-resistor input circuit — a device alarm contact wired directly, giving only closed (normal) and open (alarm) states](https://3862776825-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Feem9HLOjc53n2VxEz3Cq%2Fuploads%2Fgit-blob-e640cfdf7586e069117fc98e410f3ea34c99d54d%2FSECHUB-CR-WIRING-INPUTS-01-no-resistor-2-state.png?alt=media) ![One-resistor input circuit — R1 in series with the device alarm contact, adding a short-circuit (tamper) state](https://3862776825-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Feem9HLOjc53n2VxEz3Cq%2Fuploads%2Fgit-blob-d4501bd75fae515bd6c8a07cfef00d16b1a32cb7%2FSECHUB-CR-WIRING-INPUTS-02-one-resistor-3-state.png?alt=media) ![Dual end-of-line input circuit — R1 in series and R2 across the device alarm contact, giving the four normal/alarm/tamper/open states (the Gallagher default)](https://3862776825-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Feem9HLOjc53n2VxEz3Cq%2Fuploads%2Fgit-blob-cd28e4e92876bbb73044a68666fefa673ecdd53e%2FSECHUB-CR-WIRING-INPUTS-03-dual-eol-4-state.png?alt=media) ![Three-resistor input circuit — R1 (Alarm), R2 (Trouble) and R3 with a separate Tamper contact, giving six states including Fault and Masked (CC v8.10+)](https://3862776825-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Feem9HLOjc53n2VxEz3Cq%2Fuploads%2Fgit-blob-5bb4c20ae7e73eba6eea7e03cd8aee6efb67120e%2FSECHUB-CR-WIRING-INPUTS-04-three-resistor-6-state.png?alt=media) ## What is the typical response time of a Gallagher input? * Inputs will **not** respond to state changes that last for less than **80ms**. * Inputs **will** detect an input state change when it lasts for more than **100ms**. ## How long can the cable be to the device being monitored? This depends on the resistors at the detector and on the cable itself. Cabling should be a **minimum size of 24 AWG (0.2mm²)** for all inputs. The length is a difficult question to answer and involves a lot of variables: * The resistor resistance at the detector (input) * The cable cross-sectional area * The length of the cable The cross-sectional area, the length, and the conductor material, usually copper, determine the resistance of the cable. That resistance has to be **much lower** than the resistor value at the detector for the state at the detector to be interpreted accurately. > ⚠️ **Important:** The input circuit is designed around using the internally provided **5V** to operate. If an external voltage exceeding **15V** is connected to an input, the input **may be permanently damaged**. ## Can an active device be monitored? **No.** Gallagher requires a clean set of contacts with the resistors configured correctly to monitor the device state. An active device here means a device that outputs its own voltage in reference to a common or zero-volt terminal, rather than presenting a clean unbiased output. Gallagher hardware outputs a small voltage that it uses to measure the resistance of the connected device. If the monitored device is outputting its own voltage, the Gallagher hardware cannot detect the state. *** 🔗 **Related** * [Wiring Primer](/knowledge-hub/deployment-resources/install-and-commission/wiring-basics/wiring-primer.md). Why the default resistors are 4k7, and how much resistance the cable adds. * [Wiring Outputs](/knowledge-hub/deployment-resources/install-and-commission/wiring-basics/wiring-outputs.md). The other half of Gallagher I/O. * [Input and Output (I/O) Devices](https://github.com/GGLSecDev/gitbook-spaces/tree/main/tech-support/products/cc-hardware/input-and-output-io-devices/README.md). The hardware these inputs terminate on. Next: [Wiring Outputs](/knowledge-hub/deployment-resources/install-and-commission/wiring-basics/wiring-outputs.md) → *Source: SECHUB-CR-WIRING-INPUTS* --- # 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/deployment-resources/install-and-commission/wiring-basics/wiring-inputs.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. 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