What’s the difference between the HSM2204 and the HSM2300?
In many ways the two modules are the same. They both provide an additional 1 amp of auxiliary power and require a PTC1640 and backup battery like the BD712. While that is all that the HSM2300 adds, the HSM2204 also has 4 high current PGM outputs. The first of which acts as a supervised bell output limited to 700 mA if desired.