Regression: SIA Alarm Systems #160310
Description
The problem
Hello,
I am reporting a regression in the SIA Alarm Systems integration (pysiaalarm) affecting Ajax alarm hubs using SIA DC-09 (DIA-DCS).
Problem
After updating Home Assistant Core (currently 2025.12.5), the Ajax hub enters a constant connect / disconnect loop (approx. 9s connected / 5s disconnected).
The same configuration worked correctly in previous Core versions.
Key log message
[pysiaalarm.base_server] Code not found, replying with DUH to account: 002
From the AJAX alarm, what is observed are constant connections and disconnections with a well-defined pattern in seconds: 10 seconds connected, 5 seconds disconnected, 10 seconds connected...and so on.
Thank you for your work on Home Assistant.
Fran Hita.
What version of Home Assistant Core has the issue?
2025.12.5
What was the last working version of Home Assistant Core?
2025.12.4
What type of installation are you running?
Home Assistant OS
Integration causing the issue
SIA Alarms Systems
Link to integration documentation on our website
No response
Diagnostics information
Technical details
- Home Assistant OS
- Official SIA integration configured via UI (no YAML)
- Protocol: SIA DC-09 (DIA-DCS)
- No encryption
- Stable network, static IPs
- No configuration changes on the Ajax side
It appears that pysiaalarm does not recognize certain SIA DC-09 event codes sent by Ajax and responds with "DUH".
Ajax hubs do not accept DUH as a valid ACK, so they immediately drop the TCP connection and retry, resulting in an infinite reconnect loop.
Expected behavior
All standard SIA DC-09 event codes sent by Ajax hubs should be parsed correctly and acknowledged with a valid ACK, keeping the connection stable.
Actual behavior
Unrecognized codes trigger a DUH response, causing the Ajax hub to disconnect and reconnect continuously.
Impact
This regression makes the SIA integration unusable with Ajax alarm systems in affected Home Assistant versions.
Please let me know if additional logs or tests are needed.
Thank you for your work on Home Assistant.
Example YAML snippet
Anything in the logs that might be useful for us?
Additional information
No response