Question on connected smoke detector requirement

[Andy Sabisch]

We had our 3-year township CO inspection today and were told that we need to have smoke / CO detectors that alerted both sixes of a duplex property.  This is a new requirement from the town (which we were not aware of) and while we have detectors in there now, they are not connected between the two sides.  Has anyone dealt with this requirement and if so, what systems do you recommend.  What is there now is a hardwired system on each side but we need one that talks across the property.  Thanks