The BCPM register list only contains register addresses for circuits 1-42. To read circuits 43-84 you will need to read the same registers for circuits 1-42 on the next modbus address. For instance if the BCPM is configured to modbus address 1, you will read circuits 1-42 exactly as the register list details. For circuits 43-84 you will read the same registers using modbus address 2. This principle also applied when adding an 84 circuit BCPM to an EGX or ECC card, you will need to add the configured address and the proceeding address.