Identify Modbus registers available in Versapro

I have a Versapro project file for a Versamax PLC. Need to identify what type of variables are suitable and made available for BMS system to read. Any ideas?

Your title mentions Modbus. Modbus addresses prefixed by 4 correspond to %R memory. Modbus addresses prefixed by 3 correspond to %AI memory. Modbus addresses prefixed by 1 correspond to %I memory. Modbus addresses prefixed by 0 correspond to %Q memory.Any other memory types in the PLC need to be copied into one of those four to be available to the Modbus master.

I'm familiar with that concept on Schneider/Telemecanique processors. So it's the exact same for GE/Emerson Versamax processors also? for example a %R1582 would be available for MODBUS/TCP as 401582?

That's correct.