Legrand EMDX3 4 120 45 Modbus register map

Device identity

What a tool can read to check that this map fits the connected device (SPEC.md section 4.7). Registers with a role are read like any other register.

Sources and notes

• EMDX3 Multifunction meter Modbus Table 412045

Source: Legrand EMDX3 Measuring Unit RS485 Modbus table, cat. no. 4 120 45

• The table calls the measurement block 'input registers' but lists only function codes 3 (read) and 16 (write), so every register is read as a holding register.
• Only the sections of the table that hold measurements and settings are mapped. The 'Register Number' column of the manual is the address plus one; this map uses the address column.
• Voltages are in mV and currents in mA. Powers and energies are raw counts whose unit depends on the CT ratio (register 4608): powers are 0.01 W, 0.01 var or 0.01 VA when CT < 5000 and 1 W, 1 var or 1 VA when CT >= 5000; energies are 10 Wh to 1 MWh per count as the manual's note 2 lists by CT ratio. Use the signed block at 5400 (always in W, var and VA) when a fixed scale is wanted.
• A sign register next to each power value says if it is positive (0) or negative (1); the power itself is unsigned.
• In a 3-wire network without neutral the voltage THD and the voltage minimum and maximum registers refer to the chained voltages instead of the phase voltages (note 3 of the manual).
• Writing settings: write 0x5AA5 to register 9984, write the new values, write 0x5AA5 to 9984 again and then 0x000A to 9728 to save them. Writing 0x000B to 10240 after unlocking restores the defaults.
• The manual gives no factory serial settings: baud rate and parity are programmable, one stop bit, device address 1 to 247. The defaults in this file are the format's defaults.