CMi6140
User’s Manual English
CMi6140
User’s Manual English
page | 28 (38)
[2022-09]
V1.2
Configuration
SenML/CBOR is to be considered a
message encoding
. It defines how the messages are encoded, but
not the actual contents of the messages (which fields from the meter are included). SenML/CBOR/M-Bus
is one such encoding, but there could be several based on this SenML/CBOR specification and the
encoder version field
above defines exactly which type and version is used.
The contents of the message are defined by the
message
format. The message format sets which fields
are to be included in both the first and the subsequent records of the SenML pack.
The number of records included in a pack is set by the readout and transmit intervals. See Scheduling
Readouts for more details. If the readout interval is 120 minutes and the transmit interval is 1440 minutes
12 readouts in total will be included.
Message Size Restrictions
Each product may have different maximum payload sizes in a single telegram. Also depending on
configuration (DTLS or not for instance) the net payload size may vary. Therefore, the device shall “fill up”
as many telegrams as required to send the data. It is for the user to define a configuration that gives a
reasonable tradeoff between power consumption (send fewer telegrams) and functional requirements
(much data is sent).
If a device is configured using a
Message Format
and many readouts the data may not fit in a single
telegram. In such cases multiple telegrams shall be sent and each telegram shall be fully self-described,
i.e., contain Meter ID, timestamps etc.
Examples
Example 1:
Parameter
Value
Readout interval
60
Transmit interval
1440 (daily)
Message encoding
SenML/CBOR/M-Bus version 0
Message format
Standard
Max transmissions per day 3
This example results in the transmission of one message per day, containing 24 readings, all with the
contents defined in the Standard message format. Data is encoded using SenML/CBOR/M-Bus.
Maximum 3 unsent such messages are sent each time (if for some reason the messages were not sent
“last time”). So maximum transmitted messages per day is 3 (containing 3x24=72 readings, covering 3
days)
Example 2:
Parameter
Value
Readout interval
120
Transmit interval
720
Message encoding
SenML/CBOR/M-Bus version 0
Message format
Tariff
Max transmissions per day 2
This example results in the transmission of one message every 12h, containing 6 readings, all with the
content defined in the Tariff message format. Data is encoded using SenML/CBOR/M-Bus. Maximum 2
