You need RS232 connection.
Issue HAI1 (for example) command from URC and have HAI listen for that message.
Or you can use any ASCII text up to 10 or 12 characters.

[Link: homeauto.com]

[Link: kb.homeauto.com]

On the URC side, you could always use the port sensing and drive a relay from HAI.


[Link: remotecentral.com]


[Link: google.com]


While I'm a dealer for both URC and HAI and have that integration on TC platform and used it on CCP as well, the above links were provided with less than a min worth of google vudu.
You'll have to do a little digging; both platforms are more or less professional solutions so there will be somewhat limited open forum / web information on them.