# Check shared physical pins before assigning Axis controller I/O > Map logical Axis controller I/O to required modes and shared physical pins before assigning services. Do not treat different logical names as independent hardware resources. - Canonical URL: https://update.dsesecurity.com/updates/check-shared-physical-pins-before-assigning-axis-controller-i-o/ - Publisher: Detection Systems & Engineering (DSE Security) - Author: DSE Security Editorial Team - Published: 2026-10-29T17:41:32+00:00 - Modified: 2026-10-29T17:41:37+00:00 - Last reviewed by DSE: 2026-10-29 - Resource type: Guide - DSE priority: Advisory - Topics: Access Control, IT - Reading time: 3 minutes ## What you need to know Map logical Axis controller I/O to required modes and shared physical pins before assigning services. Do not treat different logical names as independent hardware resources. ## Potentially affected Axis products exposing the documented I/O assignment service interface; confirm actual device, hardware and software applicability before applying the proposed checks. ## DSE recommendation DSE recommends approving a pin-conflict worksheet before applying a new logical I/O assignment. ## Article Bottom line: Check the physical pin overlap behind each logical I/O choice before assigning controller services. Build the allocation from actual service requirements and returned hardware information, rather than from convenient names. ## Source fact: documented behavior Axis’s [I/O assignment service](https://developer.axis.com/vapix/physical-access-control/io-assignment-service/) explains that an I/O represents how a combination of controller physical pins can be used, rather than being identical to one physical pin. Different pins have different electrical properties, and when multiple I/O choices use the same physical pins, only one of those I/O choices can be used at a time. The documented workflow configures the consuming services first, retrieves their requirements with axisio:GetIoUserInfoList, and retrieves available I/O and pin information with axisio:GetIoInfoList. ## What the source does not establish Do not use a logical allocation worksheet as permission to wire an arbitrary device to a terminal. Require the exact controller and connected-device documentation for electrical design. Keep this API allocation check separate from egress approval, lock-power design and proof that a physical reader or door operates correctly. ## Applicability questions - Which exact controller and installed software support the documented assignment service? - Which configured door or reader service requires each I/O, and in which mode? - Do proposed logical I/O choices share any returned physical pin names? - Has a qualified installer checked the electrical requirements against the approved wiring design? ## DSE recommendation: controlled next steps The following steps are DSE recommendations based on the cited source. DSE recommends approving a pin-conflict worksheet before applying a new logical I/O assignment. - Work from an authorized controller configuration and the approved point schedule. List each consuming entity, its service identity, intended use and required mode. Read the service requirements after the relevant entities have been configured. Preserve identifiers rather than matching entities only by a repeated label such as reader or door. Mark any requirement that has not yet been resolved. - Retrieve the available logical I/O descriptions and expand each candidate into its physical pin list. For a proposed test case, compare two differently named choices that share a pin, if the device reports such a pair. Mark the pair as competing resources in the worksheet. Compare supported modes with each service requirement and refer electrical questions to the installer before making assignments. - Choose an allocation with no unresolved pin conflict and apply it only through the supported workflow in an approved test window. Read back the resulting allocation. Have the qualified installer and application owner verify the intended point operation separately. If the readback or physical behavior disagrees with the plan, restore the approved configuration rather than trying additional undocumented combinations. ## Verification and evidence Retain the service-requirement response, available-I/O response, allocation worksheet and approved wiring reference together. Highlight the pin names that justified accepting one choice and rejecting another. Record device identity and software so a replacement-controller review does not inherit an unexamined allocation. Include a desk-review rejection case: present two proposed allocations sharing a returned pin and ask the reviewer to identify the conflict before implementation. Record that exercise as a proposed planning test, not as evidence that a field wiring fault was created or that a door’s complete safety and security workflow passed. ## Official references - [I/O assignment service](https://developer.axis.com/vapix/physical-access-control/io-assignment-service/) — Axis Communications; official VAPIX documentation. Source review completed October 29, 2026. Recheck the official documentation and the deployed device’s capabilities before changing production settings. ## Primary reference - Name: Axis Communications — I/O assignment service - Authority: Axis Communications - URL: https://developer.axis.com/vapix/physical-access-control/io-assignment-service/ - Source publication date: Not stated by the source ## Citation and use Preferred citation: “Check shared physical pins before assigning Axis controller I/O,” DSE Security, https://update.dsesecurity.com/updates/check-shared-physical-pins-before-assigning-axis-controller-i-o/ Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/ Usage and citation policy: https://update.dsesecurity.com/usage/ Copyright © 2026 Detection Systems & Engineering. All rights reserved.