Yes, the Master / central unit can be T2. It still listens to the same frequency as for T1. But transmissions from the Master are on the “S” frequency, because the Slaves / sensors will listen on the “S” frequency. So you can easily migrate from a one-way to a two-way system.
Using Master in T2, you will need to use the auto messages generation, as the master must send a message in 2-3 ms after it received the messages from the Slave. See the MBUS User Manual for how to use the T2 mode and “auto message generation”.
Last Update: January 11, 2019