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define(`TITLE', `M-Bus Master, Part 3 (Water)')
define(`DATE', `2013-09-10')
define(`CONTENT', `
2018-05-02 16:30:12 +02:00
Now, also the water meter talks to me.
< a href = "http://a385e-5.de/wp-content/uploads/2013/09/Wasserzaehler.jpg" > < img src = "http://a385e-5.de/wp-content/uploads/2013/09/Wasserzaehler-225x300.jpg" alt = "Wasserzaehler" width = "225" height = "300" class = "alignnone size-medium wp-image-173" / > < / a >
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(Note the thin grey cable, that'`s the M-Bus cable.)
2018-05-02 16:30:12 +02:00
And, after a small modification of the circuit I can talk to water meter and electric power meter connected in parallel to the master.
< blockquote >
< a href = "http://a385e-5.de/wp-content/uploads/2013/09/laser-drucker_005120.jpg" > < img src = "http://a385e-5.de/wp-content/uploads/2013/09/laser-drucker_005120-209x300.jpg" alt = "laser-drucker_005120" width = "209" height = "300" class = "alignnone size-medium wp-image-192" / > < / a >
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IC2 was already added in the last step, since the output of the analog circuit and the requirements of the MCU didn'`t match concerning their logical polarity.
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Now, T3 (BS108) and R9 (2k2) have been added to disable the receive path while data is transmitted.
< / blockquote >
Responding the < code > REQ_UD2< / code > command, the water meter sends this telegram (address 0x30 has been assigned to it first):
< code >
so 10 5b 30 8b 16
success
SO RESP: 68 46 46 68 08 30 72 45 71 43 00 24 23 25 07 02 00 00 00 0C
13 51 84 00 00 8C 10 13 00 00 00 00 0B 3B 00 00 00 0B 26 62 06 00 02
5A CC 00 04 6D 17 16 A9 19 7C 13 00 00 00 00 FC 10 13 00 00 00 00 72
6C 00 00 42 EC 7E BF 1C 35 16
< / code >
A closer look, consulting the < a href = "http://www.m-bus.com/mbusdoc/md8.php" title = "M-Bus documentation" target = "_blank" > M-Bus documentation< / a > reveals the meaning:
[table]Octet(s), Field, Meaning
< code > 68 46 46 68< / code > , Preamble with length,
< code > 08< / code > , C field,
< code > 30< / code > , A field (address),
< code > 72< / code > , CI field, variable data response
< code > 45 71 43 00< / code > , Ident. No.,
< code > 24 23< / code > , Manufacturer , HYD = Hydrometer GmbH
< code > 25< / code > , Version,
< code > 07< / code > , Medium, Water
< code > 02< / code > , Access No.,
< code > 00< / code > , Status,
< code > 00 00< / code > , Signature,
< code > 0C< / code > , DIF, 8 digit BCD
< code > 13< / code > , VIF, Volume; 10^(3-6)m^3
< code > 51 84 00 00< / code > , Value, 8.451m^3
< code > 8C< / code > , DIF, ext; 8 digit BCD
< code > 10< / code > , DIFE, minimum value
< code > 13< / code > , VIF, Volume; 10^(3-6)m^3
< code > 00 00 00 00< / code > , Value, 0
< code > 0B< / code > , DIF, 6 digit BCD
< code > 3B< / code > , VIF, Volume flow; 10^(3-6)m^3/h
< code > 00 00 00< / code > , Value, 0
< code > 0B< / code > , DIF, 6 digit BCD
< code > 26< / code > , VIF, Operating time; hours
< code > 62 06 00< / code > , Value, 662h = 27.6d
< code > 02< / code > , DIF, 16bit integer
< code > 5A< / code > , VIF, Flow Temperature; 10^(2-3)°C
< code > CC 00< / code > , Value, 20.4°C
< code > 04< / code > , DIF, 32bit integer
< code > 6D< / code > , VIF, Time Point; time& date
< code > 17 16 A9 19< / code > , Value,
< code > 7C< / code > , DIF, LSB; value during error state; 8 digit BCD
< code > 13< / code > , VIF, Volume; 10^(3-6)m^3
< code > 00 00 00 00< / code > , Value, 0
< code > FC< / code > , DIF, ext; LSB; value during error state; 8 digit BCD
< code > 10< / code > , DIFE, tariff 1
< code > 13< / code > , VIF, Volume; 10^(3-6)m^3
< code > 00 00 00 00< / code > , Value, 0
< code > 72< / code > , DIF, LSB; value during error state; 16bit integer
< code > 6C< / code > , VIF, Time Point; date
< code > 00 00< / code > , Value, 0
< code > 42< / code > , DIF, LSB; 16bit integer
< code > EC< / code > , VIF, ext; Time Point; date
< code > 7E< / code > , VIFE, ??
< code > BF 1C< / code > , Value,
< code > 35< / code > , Checksum,
< code > 16< / code > , Stopbyte,
[/table]
Decoding of the time& date type is done like this:
< pre >
if (t_data)
{
if (t_data_size == 4) // Type F = Compound CP32: Date and Time
{
if ((t_data[0] & 0x80) == 0) // Time valid ?
{
t-> tm_min = t_data[0] & 0x3F;
t-> tm_hour = t_data[1] & 0x1F;
t-> tm_mday = t_data[2] & 0x1F;
t-> tm_mon = (t_data[3] & 0x0F) - 1;
t-> tm_year = ((t_data[2] & 0xE0) > > 5) |
((t_data[3] & 0xF0) > > 1);
t-> tm_isdst = (t_data[1] & 0x80) ? 1 : 0; // day saving time
}
}
else if (t_data_size == 2) // Type G: Compound CP16: Date
{
t-> tm_mday = t_data[0] & 0x1F;
t-> tm_mon = (t_data[1] & 0x0F) - 1;
t-> tm_year = ((t_data[0] & 0xE0) > > 5) |
((t_data[1] & 0xF0) > > 1);
}
}
< / pre >
(Found on github in the libmbus repo.)
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')
