Embrasul MD20 Modbus register map

Sources and notes

• Manual de Instalação e Operação do MD20
  Sections 7 and 8, supplied with the map request

Source: Embrasul, Manual de Instalação e Operação do MD20, section 7 (Modbus RTU) and section 8 (register list)

• Register addresses are the decimal ones in the manual, used as they are (address_base 0): the manual's read example for the phase voltages sends start address 1000 (0x03E8). Function 0x03 reads; function 0x10 writes.
• Data bytes are sent high byte first and the example (0x435C0000 = 220) shows a 32-bit float with the high word first, so the word order is big. The manual does not state the word order of the 32-bit integers; big is assumed.
• Registers marked R/WC in the manual (clock, communication, power parameters and the others) are changed with the configuration command block: write an instruction code and its parameters with function 0x10 at registers 300 to 423, then read the result code at 425 (0 = accepted). They are marked read-only here because they cannot be written directly. The instruction codes are in sections 8.1 to 8.8 and are not mapped.
• Energy registers are integers in 0.1 kWh, 0.1 kvarh and 0.1 kVAh; the scale of 0.1 gives kWh, kvarh and kVAh.
• Names follow the manual's aliases. I1VGMax and I1VGMin in the manual are the maximum and minimum of the average three-phase current; the manual lists phase B minimum power at 6078, which is taken as the 6072 the sequence implies.
• The peak demand dates (5120, 5128, 5136), the demand reset time (5002) and the unmapped date-time values use four registers of the manual's date format and are not mapped.
• Serial settings: 2400, 4800, 9600 or 19200 baud, no, odd or even parity, 8 data bits, 1 stop bit, address 1 to 247. Defaults are 9600 baud, no parity, address 1.