When the MVI71-MCM is connected using Side-Connect, can a Modbus Master device read and write to the same Modbus address in the module?

Yes, a Modbus master can read and write to the same address in the MVI71-MCM module when side-connect is used. In the configuration file, the read start and write start values should both be set to the same value (e.g. read start = 0, write start = 0).