IP Alarm Triggers

Does anyone know if there is a device that would take http requests and would trigger an alarm relay on itself?

There are several options for this. Suitability depends on what extent you mean 'http request', which I assume is integrateability to other ethernet based devices.

One option is the ADAM relay, a TCP/IP 6 I/O channel relay.

Other options might be the Axis P8221, which is essentially an IP relay, not only an audio interface module.

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