define(`TITLE', `M-Bus Master, Part 2 (Electricity)') define(`DATE', `2013-09-09') define(`CONTENT', `

Finally, this MeterBus transceiver is connected to an Arduino Ethernet board and talks to an M-Bus equipped electric powermeter

The power meter was configured to M-Bux address 0x21, and so the initialize command, sent through the Arduino and the transceiver has been answered correctly:


so 10 40 21 61 16
success
SO RESP: E5

so is the command for the firmware to send the following octets on the bus, success is the acknowledgement, that this has been done and SO RESP: is the prefix for the octets received from the bus. According the the manufacturers documentation the M-Bus command REQ_UD2 (see here in the M-Bus documentation should be used to request all the measurement data from the powermeter, and it works: Here without any consumer load:


so 10 5b 21 7c 16
success
SO RESP: 68 38 38 68 08 21 72 99 51 00 13 2E 19 21 02 01 00 00 00 8C
10 04 06 00 00 00 8C 11 04 00 00 00 00 02 FD C9 FF 01 E3 00 02 FD DB
FF 01 00 00 02 AC FF 01 00 00 82 40 AC FF 01 00 00 EB 16

Here with an electric kettle as consumer load:


so 10 5b 21 7c 16
success
SO RESP: 68 38 38 68 08 21 72 99 51 00 13 2E 19 21 02 02 00 00 00 8C
10 04 06 00 00 00 8C 11 04 00 00 00 00 02 FD C9 FF 01 DE 00 02 FD DB
FF 01 56 00 02 AC FF 01 CD 00 82 40 AC FF 01 00 00 0A 16

In the above answer of the powermeter the important measurement values are highlighted: [table] Data,measurement category,multiplicator and unit, 06 00 00 00,total consumption,0.01kWh,0.06kWh DE 00,voltage,1V,222V 56 00,current,0.1A,8.6A CD 00,power,0.01kW,2.05kW [/table] Here is the firmware for the Arduino. This is a closer look into the response data structure: (Manufacturer IDs can be found here.) [table] Octet(s), Field, Meaning 68 38 38 68, Preamble with lentgh, 08, C Field, 21, A Field, 72, CI Field, variable data response 99 51 00 13, Ident. No., 2E 19, Manufacturer, FIN = Finder GmbH 21, Version, 02, Medium, Electricity 02, Access No, 00, Status, 00 00, Signature, 8C, DIF, ext; instantaneuos value; 8 digit BCD 10, DIFE, tariff 1; storage 0 04, VIF, Energy; 10^(4-3)Wh 06 00 00 00, Value, 0.06kWh 8C, DIF, ext; instantaneuos value; 8 digit BCD 11, DIFE, tariff 1; storage 1 04, VIF, Energy; 10^(4-3)Wh 00 00 00 00, Value, 0 02, DIF, 16bit integer FD, VIF, ext; true VIF is next; see table for secondary VIF C9, VIFE, ext; Voltage; 10^(9-9)V FF, VIFE, manufacturer specific next VIFE 01, VIFE, DE 00, Value, 222V 02, DIF, 16bit integer FD, VIF, ext; true VIF is next; see table for secondary VIF DB, VIFE, ext; Current; 10^(11-12)A FF, VIFE, manufacturer specific next VIFE 01, VIFE, 56 00, Value, 8.6A 02, DIF, 16bit integer AC, VIF, ext; Power; 10^(4-3)W FF, VIFE, manufacturer specific next VIFE 01, VIFE, CD 00, Value, 2.05kW 82, DIF, ext; 16bit integer 40, DIFE, tariff 0; storage 4 AC, VIF, ext; Power; 10^(4-3)W FF, VIFE, manufacturer specific next VIFE 01, VIFE, 00 00, Value, 0 0A, Checksum, 16, Stopbyte, [/table] ')