Operating Manual V8.2/03.2017
Non Invasive Road Sensor
46
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany
19.5 Communication in SDI-12 Mode
The communication in SDI-12 mode of the NIRS31-UMB is conforming to the standard
defined in
‘SDI-12 A Serial-Digital Interface Standard for Microprocessor-Based Sensors
Version 1.3 January 12, 2009‘. The sensor may be operated in bus mode together with other
SDI-12 sensors, connected to one SDI master (logger).
19.5.1 Preconditions for SDI-12 Operation
As the interface settings defined in the SDI-12 standard are significantly different from the
UMB default settings, some preconditions have to be met for operation:
Setting for SDI-12 mode in the configuration with UMB Config Tool (at least V1.2)
Using the UMB Config Tool the protocol mode of the station has to be set to “SDI-12”. This
will automatically set the baud rate to 1200.
Measurement data can be transmitted alternatively in metric or US units. The selection is
done by the UMB Config Tool.
Metric units
US units
When operating the device in SDI-12 mode it is basically no more possible to access the
device with the UMB Config Tool, due to the different interface parameter settings. To enable
configuration access nevertheless the interface is operated in standard UMB mode (19200
8N1) for the first 5 seconds after reset / power on. If a valid UMB telegram is received within
this time, the device will stay in UMB mode for the configured time out (several minutes) so
that the configuration can be modified.
Connect the PC to the NIRS31-UMB through an RS-485 converter (e.g. ISOCON)
Start the UMB Config Tool and create a NIRS31-UMB with the address of the actual
device and activate at least one sensor. Start the measurement (will report
connection error at first)
Reset the device (Power off / on)
When measurement values are received the measurement can be terminated, the
interface is now open for configuration.
