Issue
Otis Destination Dispatch integration with controller models MP4502 and LP4502 experiences instability where Destination Entry Controllers (DECs) repeatedly cycle online and offline, and elevator access control intermittently stops working. In some cases, controllers remain online locally but appear offline in the system, and elevators either do not respond to badges or allow free access. Temporary workarounds such as rebooting the controller, modifying IP settings, or adding/removing a reader restore operation for a limited time before the issue reoccurs.
Product Line
EcoStruxure Access Expert
Environment
- Mercury MP4502 controllers (firmware 2.7.x, 2.9, 2.10)
- Mercury LP4502 controllers (firmware 1.29.x, 1.30.x)
- Otis Destination Dispatch integration
- Otis Compass 360 system
Warning
Potential for Data Loss: Ensure all important data is backed up before proceeding.
Cause
Instability occurs when using Mercury MP4502 controllers with Otis Compass 360 Destination Dispatch systems, resulting in intermittent loss of communication between the controller and Destination Entry Controllers (DECs).
Mercury MP4502 firmware has been validated with earlier Otis Compass integrations, but not explicitly with Compass 360. In this scenario, MP4502 firmware versions (2.7.x through 2.10) establish communication over TCP port 3001, however, sessions do not remain stable, leading to repeated disconnect and reconnect behavior.
The issue does not occur when using Mercury LP4502 controllers running firmware 1.30.2, indicating a compatibility limitation between MP4502 firmware and the Compass 360 integration in this configuration.
Resolution
Stability was achieved by replacing the MP4502 controller with an LP4502 controller running firmware version 1.30.2. After this change, DEC devices no longer exhibited online/offline cycling and the integration remained stable during operation.
Additional actions taken during troubleshooting included:
- Upgrading MP4502 firmware to version 2.9, which did not resolve the instability
- Attempting firmware downgrade, which was unsuccessful
- Performing multiple temporary workarounds (controller reboot, IP refresh, configuration changes) that restored functionality only temporarily
The validated outcome is that LP4502 firmware in the 1.x branch provided stable operation for the integration, whereas MP4502 firmware versions tested did not consistently resolve the issue. Continued coordination with vendors is required for a fully supported and validated solution for Compass 360 with newer hardware.
