Communication with M-Bus
2CMC48001M0201 197 A43/A44
Revision: C User Manual
10.3 Standard Readout of Meter Data
This section describes the readout of the default telegrams containing energy and
instrumentation values etc. The data readout procedure starts when the master
sends a REQ_UD2 telegram to the meter. The meter responds with a RSP_UD
telegram. A typical readout is a multi-telegram readout. The last DIF in the user
data part of the telegram is 1F to indicate that there is more data in the next tele-
gram, or 0F if there are no more telegrams.
For EQ meters there are up to 7 default telegrams to read. In meters with internal
clock more telegrams may follow, containing previous values data. The most re-
cent values are sent out first having storage number 1, then the second most re-
cently stored values with storage number 2 and so on until all stored previous
values have been read. If no previous values exist in a meter with internal clock a
telegram is sent out where all data is marked with status byte for "No data avail-
It is also possible to read previous values starting from a specific date and back-
wards in time by sending a special read request.
Note – Note: Normally the meter is configured to send out power values as 32 bit
integers, expressed in W (or var/VA) with 2 decimals. This means that the maximum
power possible to express is approximately ± 21 MW
Below following sections is an example of a readout of the 7 default telegrams
and 2 previous values telegrams, containing the most recent snapshot of previous
values. Note that these are examples only, data types and scaling of the quantities
can differ between meters, as well as the allocation of quantities to different tele-
10.3.1 Example of the 1st telegram (all values are hexadecimal)
L-field, calculated from C field to last user data
CI-field, variable data respond, LSB first
Identification Number, 8 BCD digits
Signature (0000 = no encryption)
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