Modsak Manual v3.14 - 3. Registers
In slave mode, you must define some registers if you want Modsak to send valid responses to register read and write requests.
In master mode, you can send register read and write requests using the Define Command page, without needing to define any registers. Alternatively, you can define some registers, as described in the following sections, and use the Register Table buttons to request register reads and writes.