Lufft SHM31 User Manual

Communication in SDI-12 mode
Snow depth sensor SHM 31, V2.1 51
10.11.8. Calibrate offset command
The command starts a measuring process to determine the distance. The determined values are
set as offsets / reference heights using the stored reference angle.
Command: aXARH!
Response: aXARHok<CR><LF>
If procedures that prohibit execution of the command are active,
aXARHbusy<CR><LF>
will be the response and the command will be ignored.
10.11.9. Switch on defrost heating cycle command
The command starts the defrost heating cycle.
Command: aXHDS!
Response: aXHDSok<CR><LF>
10.11.10. Switch off defrost heating cycle command
The command switches off an ongoing defrost heating cycle if necessary.
Command: aXHDE!
Response: aXHDEok<CR><LF>
10.12. Parameter setting commands
Parameter setting commands are implemented as manufacturer-defined SDI-12 ‘extended’
telegrams and are used to read out and set parameters.
Parameter setting commands are composed of the prefix X defined in the SDI-12 standard, an
additional prefix ‘P’ for parameter, and a three-digit individual code. The code corresponds in most
cases to the corresponding code of the ASCII2.0 protocol.
If the command is sent without a setting value added, the currently valid parameter value is
returned.
The setting value is to be formatted according to SDI-12 number conventions (i.e. always with a
leading sign and a maximum of seven digits, plus a decimal point if necessary). Regardless of the
number type of the parameter to be set, both floating point and integer values are accepted. For
integer parameters, a floating point entry is rounded if necessary.
The given setting value is checked against the respective parameter’s limits. If the permissible
range is exceeded, the command is rejected with ‘invalid’ or ‘invalid-’ (impermissible negative
value) added.
If the command with setting value was successfully received, the telegram is answered with the
set value added to the command code.
If the three-character command code is unknown,
aX_noCmd<CR><LF>
will be the response.
10.12.1. Retrieving the current parameter setting
Command: aXPccc!
ccc: Three-character parameter code; see table
Response: aXPccc<+/->nnn<CR><LF> for integer parameters, nnn: Parameter
aXPccc <+/->fff.f<CR><LF> for floating point parameters
The number of nnn or fff digits is variable according to the parameter value:
aX_noCmd<CR><LF> in case of unknown parameter code ccc
Example: Retrieving the currently set laser measurement intervals, SHM 31-UMB with SDI-12 ID
‘0’
0XPLMI!

Lufft SHM31 Specifications

General

Brand	Lufft
Model	SHM31
Category	Accessories
Language	English