Operating Manual

IRS31Pro-UMB Operating Manual V10 / 01.2020
G. Lufft Mess- und Regeltechnik GmbH 53
(*) Remark: The 5 seconds UMB communication are available from program start. Under consideration of
the operating system start, where no communication is possible, the device will be ready for SDI12
requests after 7.0 – 7.5 seconds.
18.5.2 Command Set
For details of the SDI-12 protocol please refer to the above mentioned standard document.
Following commands are available for the IRS31Pro-UMB:
Note: The examples in the following sections use italics to print the requests from the logger (0V!)
Command Function
?! Address search (Wildcard request, one device only on bus!)
a! Request device active?
aI! Request device identification
aAb! Address change to b ( 0 … 9, A …Z, a … z)
aM! Measurement basic minimal data set
aMC! Measurement, basic minimal data set, transmit values with CRC
aC! Concurrent measurement, full basic data set
aCC! Concurrent measurement, transmit values with CRC
aD0! Data request buffer 0
aD1! Data request buffer 1
aD2! Data request buffer 2
aR0! Data request from continuous measurement, data set 0
aR1! Data request from continuous measurement, data set 1
aR2! Data request from continuous measurement, data set 2
aRC0! Data request from continuous measurement, data set 0 with CRC
aRC1! Data request from continuous measurement, data set 1 with CRC
aRC2! Data request from continuous measurement, data set 2 with CRC
aV! Command verification: Evaluate sensor status and heating
temperatures, data request with aD0!, aD1!
Command Function
aXU<m/u>! Change the unit system for SDI data
aXA<a/C>! Change between average and spot value transmission
aXD<n/m/c>! Select defrosting agent (currently not yet available)
aXM+nnn! Set threshold for road condition “moist”
aXW+nnn! Set threshold for road condition “wet”
aXT+nn.n! Set temperature threshold for critical road conditions
aXR! Device reset
Due the applied measurement processes the device will, different from other sensors described in the
SDI-12 document, in always measure continuously. This causes some special properties:
 The device does not need a “Wakeup” and does not have a sleep mode. So the reactions to
“Break” signals and any related timings are inapplicable. “Break” will be ignored.
 Data requested with M- or C- commands are always available immediately. The device will
always respond with a000n resp. a000nn. This means the device will not send any service
request and will ignore measurement abort signals. The logger should request the data
immediately.
 M- and C- command only differ in the number of values made available in the buffers (in both
cases the maximum permitted by the standards of 9 resp. 20).