ML-x17 DATA LOGGER MANUAL
Manufacturers of low power instruments
page 81
In example: (ACME/METEOSTATIONS/STATION_001). Your central monitoring system could subscribe
to all topics starting with ACME and when a logger publishes for the first time, then your system could
create a profile for "STATION_001" based on the specified "METEOSTATIONS" classification.
Clearing the ‘Root topic’ will set it back to the default YDOC/<SN>
The logger uses the following publishing topics:
•
<root>/sensors/<parameter code>
to publish an "Actual value" of a specific parameter.
•
<root>/data/jsn
to publish the "Log data" in JSON format.
•
<root>/data/csv
to publish the "Log data" in CSV file format.
•
<root>/data/txt
to publish the "Log data" in YDOC native text format.
•
<root>/alarm/sys
to publish "System alarms" in plain text, e.g. about a failing sensor.
•
<root>/alarm/data
to publish "Data alarms" in plain text, e.g. about reaching a low tank level.
•
<root>/jpg/<yymmdd_hhmmss>
to publish "Camera pictures with timestamp" in JPEG format.
•
<root>/status/time
the time of the logger at start of the MQTT session (yyyy/mm/dd hh:mm:ss).
4.25.5 Client ID
Every MQTT client should connect with a unique client identification for which we use the unique IMEI-
number of the built in modem. If necessary you can specify your own client ID.
4.25.6 Clean Session
Only check this option
if your MQTT-
broker requires it, else you won’t be able to do remote
configuration or “over the air” configuration updates or firmware upgrades anymore.
4.25.7 Data format
The MQTT-driver can be configured to transfer its historical data in various payload formats (csv, txt and
json) and is provided with a Sparkplug B option as well. Sparkplug-B is becoming a defacto IIoT standard
to easily connect to industrial systems like SCADA systems. See Chapter
‘Sparkplug-B Data Format’ for
more info and deployment options.
4.25.8 Max Payload
In circumstances like a network outage a data log file can grow bigger than the maximum topic payload
allowed by your MQTT-broker. Please specify the limit if any and the logger will chop the payload in parts.
4.25.9 Input Parameters
Another MQTT-client is able to transmit up to 8 different parameters to the data logger. Such a parameter
can, like any other sensor parameter, be logged, alarmed up on or used in a derived channel (e.g. a
calculated channel that evaluates to an alarm condition, in example when a level exceeds x and flow
exceeds y).
An MQTT-client can publish a numeric value to one of the defined input parameters with the following
topic format:
“YDOC/<device serial number>/inputs/<parameter code>” (e.g.
YDOC/1234567/inputs/MAXLEV
). The payload should contain the numeric value in plain text
presentation, using dot as decimal separator.
Note
: The topic must be published with QOS=1, else the broker will not retain it till the next logger
connection.
