Lufft SHM 31 User manual

Snow depth sensor SHM 31, V2.1
Dear User,
Please read this user manual carefully before commissioning the SHM 31 snow depth sensor. We reserve the right
to further develop this device in line with technical progress.
OTT HydroMet Fellbach GmbH
Gutenbergstrasse 20
70736 Fellbach
Germany
Phone: [phone]
Hotline: [phone]
Fax: [phone]
Email: [e-mail] (Sales, Repairs)
Email: [e-mail] (Technical Support)
This manual was published in: June 2023
Document number: 48.7230-SHM31EN
Date
Issue
Change log
30/04/2017
Rev. 1.0
Published for the first time
08/05/2018
Rev. 1.3
Sections 7 and 11 revised; various minor changes
20/06/2018
Rev. 1.4
Modbus section inserted
08/11/2018
Rev. 1.9
‘SDI-12 for v1.4’ section extended; various revisions
30/06/2023
Rev. 2.1
Safety instructions, new data telegrams, various revisions
This manual is protected by copyright. No part of this manual may be reproduced in any way (by photographing,
photocopying, etc.) or processed, duplicated or distributed using electronic systems without the written consent of
OTT HydroMet. The manual has been edited with due care. No liability is accepted for damage resulting from
failure to observe the information contained in this manual.
We reserve the right to adapt the manual in line with the device’s technical further development.

Snow depth sensor SHM 31, V2.1
Contents
1. Read before commissioning ......................................................................................................................................5
1.1 Symbols used ......................................................................................................................................................5
1.2 Safety instructions ...............................................................................................................................................5
1.3 Notes on laser safety and laser classification......................................................................................................5
1.4 Intended use........................................................................................................................................................6
1.5 Incorrect use........................................................................................................................................................6
1.6 Brand names used ..............................................................................................................................................6
2. Item names and technical data ..................................................................................................................................7
2.1. Labelling ..............................................................................................................................................................7
2.2. Technical data .....................................................................................................................................................8
2.3. Scope of delivery .................................................................................................................................................9
2.4. Additional documents and software...................................................................................................................11
3. Description of the device .........................................................................................................................................12
3.1. Basic principles of the measurement method....................................................................................................12
3.2. Introduction to assembly and commissioning ....................................................................................................12
3.3. Sensor heating ..................................................................................................................................................13
4. Generating the measured values.............................................................................................................................14
4.1. Measured values (curr, avg)..............................................................................................................................14
4.2. Normal mode .....................................................................................................................................................14
5. Assembly ...................................................................................................................................................................15
5.1. Assembly instructions........................................................................................................................................15
5.2. Assembly...........................................................................................................................................................15
6. Connections ..............................................................................................................................................................17
6.1. Connecting the device .......................................................................................................................................17
6.2. Connector pin assignment.................................................................................................................................17
6.3. Recommended cable shield connection ............................................................................................................17
6.4. Supply voltage ...................................................................................................................................................17
6.5. Data interfaces ..................................................................................................................................................17
6.6. Heating release .................................................................................................................................................17
7. Commissioning .........................................................................................................................................................18
7.1. Important information for commissioning...........................................................................................................18
7.2. Switching on ......................................................................................................................................................18
7.2.1. Settings over RS232 or RS485 ...............................................................................................................18
7.3. UMB ConfigTool.NET ........................................................................................................................................18
7.3.1. Basic installation with ConfigTool.NET and a serial interface .................................................................18
7.3.2. The SHM 31’s sensor parameters ..........................................................................................................26
8. Communication over UMB-ASCII 2.0.......................................................................................................................29
8.1. Syntax................................................................................................................................................................29
8.2. Checksum..........................................................................................................................................................29
8.3. Examples...........................................................................................................................................................29
8.4. Description of the data telegram #1 with an example ........................................................................................30
8.5. Angle adjustment...............................................................................................................................................30
8.6. Switching from UMB protocol to ASCII protocol ................................................................................................30
8.7. ASCII command overview .................................................................................................................................31
9. UMB communication ................................................................................................................................................37
9.1. Factory settings .................................................................................................................................................37
9.2. Overview of measuring channels.......................................................................................................................37
9.3. Communication in binary protocol .....................................................................................................................39
9.3.1. Data frame ..............................................................................................................................................39
9.3.2. Addressing with class ID and device ID ..................................................................................................39
9.3.3. Example of creating addresses...............................................................................................................39

Snow depth sensor SHM 31, V2.1
9.3.4. Example of a binary protocol query........................................................................................................ 39
9.3.5. Status and error codes in the UMB binary protocol................................................................................ 40
9.3.6. CRC calculation ..................................................................................................................................... 41
10. Communication in SDI-12 mode ............................................................................................................................. 42
10.1. Connector pin assignment ................................................................................................................................ 42
10.2. Settings for using SDI-12.................................................................................................................................. 42
10.3. Exiting SDI mode .............................................................................................................................................. 42
10.4. Command overview .......................................................................................................................................... 43
10.5. Setting the address........................................................................................................................................... 44
10.6. Measured data telegrams ................................................................................................................................. 44
10.6.1. Example: C and M queries of the SHM 31-UMB .................................................................................... 45
10.6.2. Buffer assignment – basic data – SHM 31-UMB .................................................................................... 45
10.7. Additional measuring commands...................................................................................................................... 46
10.8. Device identification telegram ........................................................................................................................... 47
10.9. Telegram verification......................................................................................................................................... 47
10.10. Query measured value parameter command (SDI-12 v1.4) ............................................................................ 48
10.11. Switching commands....................................................................................................................................... 49
10.11.1. Unit system changeover command ........................................................................................................ 49
10.11.2. Device reset command........................................................................................................................... 49
10.11.3. End measurement command ................................................................................................................. 50
10.11.4. Start measurement command ................................................................................................................ 50
10.11.5. Laser on command................................................................................................................................. 50
10.11.6. Laser off command................................................................................................................................. 50
10.11.7. Calibrate offset and angle command...................................................................................................... 50
10.11.8. Calibrate offset command ...................................................................................................................... 51
10.11.9. Switch on defrost heating cycle command ............................................................................................. 51
10.11.10.Switch off defrost heating cycle command ............................................................................................. 51
10.12. Parameter setting commands.......................................................................................................................... 51
10.12.1. Retrieving the current parameter setting ................................................................................................ 51
10.12.2. Setting the parameter setting ................................................................................................................. 52
11. Communication in Modbus mode........................................................................................................................... 53
11.1. Modbus connection and communication parameters........................................................................................ 53
11.2. Addressing........................................................................................................................................................ 53
11.3. Modbus functions.............................................................................................................................................. 53
11.3.1. 0x03 Read Holding Registers, 0x06 Write Single Register, 0x16 Write Multiple Registers function ...... 53
11.3.2. 0x04 Read Input Registers function ....................................................................................................... 55
12. Checking the signal quality..................................................................................................................................... 59
12.1. Application ........................................................................................................................................................ 59
13. Service, maintenance and technical support......................................................................................................... 61
13.1. Firmware update............................................................................................................................................... 61
13.2. Maintenance ..................................................................................................................................................... 61
13.3. Faults................................................................................................................................................................ 63
13.3.1. Possible indications of error on the snow depth sensor ......................................................................... 63
13.3.2. Potential interferences that may affect correct functioning..................................................................... 63
13.3.3. Error codes............................................................................................................................................. 63
13.4. UMB status codes............................................................................................................................................. 64
13.5. Disposal information – within the EU ................................................................................................................ 65
13.6. Disposal information – outside the EU.............................................................................................................. 65
13.7. Repair / maintenance........................................................................................................................................ 65
13.8. Technical support.............................................................................................................................................. 65

Read before commissioning
Snow depth sensor SHM 31, V2.1 5
1. Read before commissioning
Please read the operating manual carefully and keep it for future reference. Please note that various
components of the device and the described software may look slightly different from the figures provided in
this operating manual.
1.1 Symbols used
Warning – potential hazards for the user
Important information for correct device functioning
Reference to potential hazards for the user due to laser radiation
1.2Safety instructions
•Only adequately qualified specialists may assemble and commission the device.
•Never take measurements on or touch live parts.
•The sensor has a dead weight of approx. 2 kg and can cause injuries if dropped.
Carry the sensor with both hands to prevent the weatherproof protective hood
from sliding off the sensor.
•Parts can fall off, especially during assembly. Avoid risks by first of all transporting
and fully assembling the sensor without the hood and only putting the
weatherproof protective hood on the sensor afterwards. Ensure that no
components can come loose and fall down once installation is complete.
•The mast mount may have sharp edges due to the manufacturing process.
•Use suitable occupational safety equipment during assembly and take safety
measures to prevent injuries.
•Observe the technical data, storage conditions and operating conditions.
1.3 Notes on laser safety and laser classification
The SHM 31 is a Laser Class 2 product according to the international standard IEC 60825-
1: 2014-03. Class 2 laser products are only safe for short-time exposure of the beam to the
eyes (< 0.25 s). Prolonged exposure to the laser beam may damage the eyes. Avoid
staring into the beam or pointing it towards humans or animals. The wavelength of the
laser measuring device used here is in the red, visible spectral range. Living creatures’
natural eyelid reflex helps to ensure that no damage occurs. But you should still
deliberately turn your head away when the laser beam’s light enters your eyes. Especially
in low ambient light conditions, Laser Class 2 products can lead to temporary dazzling and
considerable distraction.

Read before commissioning
6Snow depth sensor SHM 31, V2.1
Maximum radiant output power
0.95 mW
Wavelength
635 nm
Pulse duration
>400 ps
Pulse repetition rate
320 MHz
Beam divergence
0.16 mrad x 0.6 mrad
Attention
Do not look into the laser beam or point the laser beam towards people or animals! Only
authorised, trained personnel should have access to the laser sensor.
1.4Intended use
•The device must only be operated within the range of the specified technical data.
•The device must only be used under the conditions and for the purposes it was designed
for.
•The device must not be modified or converted; its operational safety and functionality
are then no longer guaranteed.
The following basic use is considered to be intended:
•Measuring distances from fixed targets.
•Measuring snow depth as a distance from the snow surface.
•Assembling the sensor on a mast or mast bracket with the line of sight below a tilt angle
towards the ground, (also see the notes on laser safety).
•Regular cleaning, checking measured results and maintenance.
1.5 Incorrect use
If the device is not assembled correctly:
•It may not work, or may only work to a limited extent
•It may be permanently damaged
•It may fall down and hurt someone
If the device is not connected properly:
•It may not work
•It may be permanently damaged
•It may cause an electric shock under certain circumstances
1.6Brand names used
All brand names used in this manual are subject to the valid trademark rights and ownership rights of the
respective owner without restriction.

Item names and technical data
Snow depth sensor SHM 31, V2.1 7
2. Item names and technical data
Item
Item number
SHM 31 snow depth sensor
8365.30
Mast strap clamp for mast measuring up to
80 mm in diameter
8365.608-11
Mast strap clamp for mast measuring up to
300 mm in diameter
8365.609-11
Mast clamp for mast measuring up to 72 mm
in diameter
8365.610-11
Connection cable (15 m)
8365.KAB015
Reference target plate set
8365.KWK-SET
UMB ConfigTool.NET software
https://www.lufft.com/download/software-lufft-configtool-net/
Replacement sensor module
8365.30-SEN
Table 1: Item numbers
2.1. Labelling
The following stickers are attached to the product.
Figure 1: Laser warning with technical data
Figure 2: Rating plate with serial number

Item names and technical data
8Snow depth sensor SHM 31, V2.1
2.2. Technical data
Category
Name
Value
Measuring parameters
Snow depth
0 – 15 m
Accuracy
± (5 mm + 0.06%)
Repeatability
0.6 mm
Precision, reproducibility
5 mm
Signal intensity (normalised)
0 – 255
Installation
Assembly height / measuring
distance
0.1 – 16 m
Tilt angle to the vertical position
10 – 30 degrees
Data interface
RS485
-UMB binary protocol (19200 Bd, variable)
-UMB-ASCII 2.0
-Modbus RTU
-Modbus ASCII
SDI-12
-SDI-12 protocol
RS232
-UMB-ASCII 2.0 protocol (9600 Bd, fixed)
RS485 and SDI-12 share the same connectors and cannot be used in parallel. RS232 uses separate
connectors and can be operated in parallel with RS485 or SDI-12.
Data transfer
Polling: UMB, UMB-ASCII 2.0, SDI-12,
Modbus
Auto Send function: UMB-ASCII 2.0
Operating parameters
Temperature range:
Without heating:
-40°C – + 50°C
-10°C – +50°C (laser inactive < -15°C)
Rel. humidity
0 – 100%
Power supply
12 or 24 V DC, tolerance ±15%
Connected load with heating
18 W
Average consumption without
heating
0.7 W
Average consumption with 10 s
measurement interval and window
heating switched on
3.4 W
MTBF @ 25°C / 40°C
88,000 h / 50,000 h
Connection cable length while using
the RS232 interface
1
≤15 m
Safety
Laser safety
Laser Class 2 (IEC 60825-1:2014)
Protection rating
IP68
EMC
EN 61326-1:2012 (industrial standard)
EU Directive
EMC 2014/30/EU, ROHS 2011/65/EU
Size, weight
Sensor size (LxWxH)
302 x 130 x 234 mm
Sensor weight
2.35 kg
Packaging size
400 x 240 x 180 mm
Weight incl. packaging
3.4 kg
Storage conditions
Temperature; rel. humidity
T={-25°C – +70°C}; rH < 100%
Table 2 2: Technical data
1If connection cables > 15 m are used, transfer problems may occur over RS232. Additionally, the voltage
drop over the cable length must be taken into account.

Item names and technical data
Snow depth sensor SHM 31, V2.1 9
Figure 3: SHM 31 dimensions, technical drawing
2.3. Scope of delivery
Depending on the order, the delivery consists of the standard scope of delivery (see
Figure 4) and additional components (see Figure 5 to Figure 9).
Figure 4: Standard scope of delivery 8365.30, consisting of sensor, test report, quick start guide and
USB stick with additional software and documents

Item names and technical data
10 Snow depth sensor SHM 31, V2.1
SHM31
8365.30
Mast mount
8365.610-11
Connection cable
8365.KAB015
Figure 5: SHM 31 sensor, here with mast mount 8365.610-11 and
connection cable
Mast mount
8365.610-11
Figure 6: Mast mount 8365.610-11
Mast mounts with steel strap
8365.608-11
or
8365.609-11
Figure 7: Mast mount with assembly clamp and steel strap, here for
masts up to Ø = 300 mm (l = 1,000 mm)