Campbell Scientific SHM 30 Snow Depth Sensor Instruction Manual

INSTRUCTION MANUAL
SHM 30 Snow
Depth Sensor
January 2015
Copyright © 2015
Campbell Scientific (Canada) Corp.
WARRANTY AND ASSISTANCE
This equipment is warranted by CAMPBELL SCIENTIFIC (CANADA) CORP. ("CSC") to
be free from defects in materials and workmanship under normal use and service for
twenty-four (24) months from date of shipment unless specified otherwise. *****
Batteries are not warranted. ***** CSC's obligation under this warranty is limited to
repairing or replacing (at CSC's option) defective products. The customer shall assume
all costs of removing, reinstalling, and shipping defective products to CSC. CSC will
return such products by surface carrier prepaid. This warranty shall not apply to any
CSC products which have been subjected to modification, misuse, neglect, accidents of
nature, or shipping damage. This warranty is in lieu of all other warranties, expressed or
implied, including warranties of merchantability or fitness for a particular purpose. CSC
is not liable for special, indirect, incidental, or consequential damages.
Products may not be returned without prior authorization. To obtain a Return
Merchandise Authorization (RMA), contact CAMPBELL SCIENTIFIC (CANADA) CORP.,
at (780) 454-2505. An RMA number will be issued in order to facilitate Repair Personnel
in identifying an instrument upon arrival. Please write this number clearly on the outside
of the shipping container. Include description of symptoms and all pertinent details.
CAMPBELL SCIENTIFIC (CANADA) CORP. does not accept collect calls.
Non-warranty products returned for repair should be accompanied by a purchase order to
cover repair costs.
Table of Contents
PDF viewers: These page numbers refer to the printed version of this document. Use the
PDF reader bookmarks tab for links to specific sections.
1. Introduction ................................................................ 1
2. Cautionary Statements .............................................. 1
2.1
2.2
2.3
2.4
2.5
2.6
Safety Labelling ................................................................................... 1
Standards and Directives ...................................................................... 2
General Safety Measures ..................................................................... 2
Laser Classification .............................................................................. 2
Personnel Requirements ....................................................................... 3
SHM 30 Labelling ................................................................................ 3
3. Initial Inspection ......................................................... 5
3.1
Ships With ............................................................................................ 5
4. Overview ..................................................................... 5
4.1
Mode of Operation ............................................................................... 5
4.1.1 Timing Parameter ......................................................................... 6
4.1.2 SHM 30 Heater Control ................................................................ 6
5. Specifications............................................................. 7
6. Installation .................................................................. 8
6.1
Siting .................................................................................................... 8
6.1.1 Inclination Angle .......................................................................... 9
6.2
Mounting .............................................................................................. 9
6.2.1 Mounting Clamps ....................................................................... 10
6.3
Electrical Parameter ........................................................................... 11
6.4
Data Configuration and Communication ........................................... 12
6.4.1 Start Up ....................................................................................... 12
6.5
Special Values for EEE.EEEE in Case of Errors ............................... 16
6.6
Analog Output .................................................................................... 17
6.7
Signal Strength (Signal Intensity) ...................................................... 17
6.7.1 Other Corrections ........................................................................ 18
6.8
SF in Analog Mode ............................................................................ 18
6.9
Wiring ................................................................................................ 19
6.10 CR1000 Programming Example ........................................................ 19
7. Maintenance ............................................................. 21
8. Troubleshooting ....................................................... 23
8.1
Error Codes ........................................................................................ 23
8.1.1 Start up Error Responses ............................................................. 25
i
Table of Contents
Appendix A. Determining the Correct Inclination Angle
A-1
A.1
Reference Object Technique ........................................................... A-1
A.1.1 Absolute and Relative Error ..................................................... A-2
A.2
Plumb Method ................................................................................. A-3
Appendix B. Firmware Release ................................ B-1
Figures
Figure 2-1 Label at the bottom of the SHM 30 ............................................... 3
Figure 2-2 Close up of the label from the bottom of the SHM 30 .................. 3
Figure 2-3 Laser warning label in English (standard) ..................................... 4
Figure 2-4 Laser exit ....................................................................................... 4
Figure 2-5 Label on inner housing (right hand side of housing) ..................... 4
Figure 4-1 Measuring principle of the SHM 30 .............................................. 6
Figure 5-1 SHM 30 with dimensions .............................................................. 8
Figure 6-1 Installation guide. .......................................................................... 9
Figure 6-2 8365.610-11 - standard for a Ø <72 mm mast ............................. 10
Figure 6-3 8365.608-11 specified for a mast with Ø 80 mm ........................ 10
Figure 6-4 8365.609-11 for masts upto Ø 300 mm ....................................... 10
Figure 6-5 Cable installation with mounting clamp 8365.610-11 ................. 11
Figure 6-6 Mounting clamp 8365.608-11 or 8365.609-11 ............................ 11
Figure 6-7 ‘id’ for querying the list of commands ........................................ 15
Figure 6-8 'pa' example output for a parameter set in Firmware 9.09 ........... 16
Figure 7-1 Unscrew the tube for stray light reduction to clean the mechanics
and optics. ...................................................................................... 22
Figure 7-2 Cleaning supplies: bellows, Allen key (T handle), and tube with
aperature. ....................................................................................... 22
Figure 7-3 Core sensor module LDM30.11. In case of service, only these core
components need to be exchanged in the field. .............................. 23
Figure 8-1 Technique for determining the angle of inclination .................. A-2
Figure 8-2 Plumb procedure: ɑ = arcsin (y/ x1) .......................................... A-3
Tables
Table 6-1 Default Configuration Parameters ................................................ 12
Table 6-2 Changing from automode ('sry') to polling mode ('srn') ............... 14
Table 6-3 Wiring ........................................................................................... 19
Table 7-1. Cleaning Schedule and Action .................................................... 21
Table 8-1. Error Codes ................................................................................. 24
Table 8-2. Message Responses and Analog Feedback for Error Codes ....... 25
Table 8-3 Firmware Releases ...................................................................... B-1
ii
SHM 30 Snow Depth Sensor
1.
Introduction
The SHM 30 measures snow depth. The SHM 30 is able to reliably determine
snow depths of up to 10 meters within seconds and with millimeter precision.
Based on an opto-electronic distance sensor emitting visible, eye-safe laser
light, the SHM 30 allows for probing distances of up to 30 m to detect the
surface level.
The SHM 30 snow depth sensor emits modulated visible laser light and
determines the distance to an object by comparing phase information. The
SHM 30 allows for operation in automatic and polling mode for the digital
output. Furthermore an analog current output is available for snow depth.
The SHM 30 is manufactured by Jenoptik.
Before using the SHM 30, please study:
x
x
x
Section 2, Cautionary Statements
Section 3, Initial Inspection
Section 4, Quick Start
More details are available in the remaining sections.
2.
Cautionary Statements
x
2.1
For handling, shipment, or transportation, the SHM 30 must be duly
packaged and placed in the correct transporting position.
Safety Labelling
Danger - Laser Hazard
Danger - Electrical Hazard
Caution -Warning of potential damage
Caution - Warning of hot surface
1
SHM 30 Snow Depth Sensor
2.2
Standards and Directives
To guarantee the safe operation of laser devices, all binding standards,
directives, and instructions regarding laser safety and laser radiation protection
must be observed by manufacturers and users (refer to Declaration of
Conformity).
The SHM 30 Snow Depth Sensor is built and tested for compliance with
the following standards and directives:
1. Council Directive 2004/108/EC on the harmonization of the laws of the
Member States relating to electromagnetic compatibility (EMC), conforming to
EN 61326 standard requirements.
2. In accordance with IEC/EN 60825-1:2007 and in terms of inherent risk
potential, the SHM 30 qualifies as a class 2 laser device.
2.3
General Safety Measures
x
x
x
x
x
x
2.4
All safety notes in this Instruction Manual including any other
applicable documents, must be duly observed and followed.
Caution – use of controls or adjustments or performance of
procedures other than those specified herein may result in
raditation exposure!
The Instruction Manual must be kept within easy reach of
personnel at all times.
The SHM 30 Snow Depth Sensor shall be powered by a safety
extra low voltage source ‘SELV’. You must ensure that under
normal conditions, the voltage does not exceed 30 VDC and in
case of a first malfunction 70 VDC.
Do not open the inner sensor housing (with the label ‘LDM
30.11’). There is serious danger of laser radiation or electrical
shock. Unauthorized intervention into the inner product will void
any warranty claims.
Cable connectors must not be plugged or unplugged, as long as
voltage is supplied.
Laser Classification
SHM 30 is a class 2 laser product, as defined in the standard IEC 60825-7:2007
and a class II product under 21CFR1040.10. In case of an accidental short time
laser exposure, the human eye is sufficiently protected by its own blinking
reflex and by turning the head away. This natural reflex may be impaired by
medication, alcohol, and/or drugs. Although the product can be operated
without taking special safety percautions, one should refrain from directly
looking into the laser beam.
Caution: Class 2 laser radiation. Maximum laser power <1 mW,
wavelength 650 nm (red laser light).
So not direct the laser beam towards other people(s)! Do not look into the
beam!
2
SHM 30 Snow Depth Sensor
2.5
Personnel Requirements
x
x
2.6
The SHM 30 shall only be installed and commissioned by properly
trained personnel having completely read and understood this
Instruction Manual.
Personnel working with the SHM 30 shall not be in a state of fatigue
or under the influence of alcohol, or medication, or have physical
impairments of any kind that might temporarily or lastingly restrict
their attention or judgement.
SHM 30 Labelling
Figure 2-1 Label at the bottom of the SHM 30
Figure 2-2 Close up of the label from the bottom of the SHM 30
3
SHM 30 Snow Depth Sensor
Figure 2-3 Laser warning label in English (standard)
Figure 2-4 Laser exit
Figure 2-5 Label on inner housing (right hand side of housing)
4
SHM 30 Snow Depth Sensor
3.
Initial Inspection
3.1
x
Check the contents of the shipment. If thers is a shortage (see Section 3.1,
Ships With), contact Campbell Scientific. If any damage has occurred
during transport, immediately file a claim with the carrier and contact
Campbell Scientific to facilitate repair or replacement.
x
Check the model number against the shipping documents to ensure the
correct product is received.
Ships With
x
x
x
x
x
x
4.
Laser labels in local language (optional)
Setup instructions and sensor protocol
CD (software and manual)
Mounting clamp (separate order required)
Knurled screws
10 m interface cable
Overview
4.1
Mode of Operation
The SHM 30 show depth sensor emits modulated visible laser light and
determines the distance to an object by comparing phase information (see
Figure 4-1). Figure 4-1 demonstrated the SHM 30 measuring principle. A
single measurement is done within 0.25 s, including time for data handling.
The snow depth sensor is analyzing the intensity of waves (signal strength), the
number of waves, and the vector to get a precise measurement. The precise
distance is determined using five different frequencies. The redundancy in
measurements higher accuracy on difficult targets or during precipitation
events. For snow depth measurements, the longest time interval (average of 25
measurements at 0.25 s) is selected, so that the sensor can measure while
filtering out noise effectively.
To calculate snow depths automatically, the user can first perform a baseline
measurement, which is stored as an offset value in the instrument. A manual
offset value for existing snow depths can also be set in either the SHM 30 or
datalogger program.
The SHM 30 allows for operation in automatic and polling mode for digital
output. Additionally, an analog current output is available for the snow depth.
In all modes, the user can tilt the sensor and correct its position using a zenith
angle ‘sp.’ Additionally, the unit of measured values can be changed from
meters (default), by changing the parameter scale factor ‘sf.’
Note
Unwanted measurement results (hard targets from snowflakes) are
filtered out using a plausibility method and the measuring time.
5
SHM 30 Snow Depth Sensor
Figure 4-1 Measuring principle of the SHM 30
4.1.1 Timing Parameter
The timing parameter ‘xt’ defines the sequence of measurements. ‘xt’ will
always be larger than the real-time internal measurement, which in general is
6.5 seconds, plus sufficient time needed to transmit the data message and
communicate with the sensor. Due to the serial sequence of command
processing, a sensor commincation throughout the measuring process is not
available.
In the automatic measuring mode, the sensor transmits its message after each
measurement. While in polling mode, in renews its measuring data in an
internal buffer.
Note
The user can query the snow depth message as often as wanted
using the command ‘xw’ to receive the latest message.
4.1.2 SHM 30 Heater Control
The SHM 30 (8365-11) has an additional heater off option. The user must
apply a 5 to 24 VDC to the brown ‘CUSTOM1’ wire to switch on the internal
heater function mode. A supplied voltage between 0 to 0.4 VDC or a
disconnected ‘CUSTOM1’ wire, switches off the internal heater permanently.
The function was integrated to prevent battery powered systems from
discharging.
6
SHM 30 Snow Depth Sensor
5.
Specifications
Dimensions (l x w x h):
302 x 130 x 234 mm
Weight:
approx. 3.3 kg
Temperature Range:
-40°C to +50°C
Relative Humidity:
0 to 100%
Heating Activity:
<0°C programmable
Measurement Parameters
Measurement Range:
0 to 10 m
Distance to Hard Targets:
0.1 to 30 m (without far field stray light
protection on natural diffuse reflecting
surfaces)
Reproducibility:
< ± 0.5 mm (on natural, diffuse reflecting
surfaces)
Measuring Accuracy:
± 1 mm (on natural, diffuse reflecting
surfaces; offset corrected sensor; 95%
statistical spread)
Measuring Accuracy Snow:
< ± 5 mm (95% statistical spread)
Programmable Measuring Interval: 1 to 600 seconds
Time for Single Measurement:
≤ 10 seconds
Measured Distance Resolution:
0.1 mm
Signal Strength (white target
with 85-90% reflectivity):
10 ± 3 (measuring range 0.8 – 10 m)
Signal Strength (black target
with 5-7% reflectivity):
1 ± 0.5 (measuring range 0.8 – 10 m)
Interfaces
Data Connection RS-232:
9600 Baud; 8N1
Data Interfaces:
RS-232, analog output
Interfaces Modes RS-232:
2.4 to 38.4 kBaud, 8N1 format
Analog Interface:
3 mA and 4 – 20 mA
Operating Modes:
Polling
Automatic message
Client Software:
Any terminal program
7
SHM 30 Snow Depth Sensor
Electrical Parameters
Power Consumption:
0.5 to 1 W (without heating)
<12 W (with heading – heating cycle
0°C to -30°C, at 24 VDC) to 24 W
Operating Voltage:
10 to 30 VDC (without heating)
15 to 24 VDC (with heating)
Figure 5-1 SHM 30 with dimensions
6.
Installation
6.1
Siting
The SHM 30 is usually mounted tilted away from the sun. The best
measurement results are achieved with an inclination angle between 10-30° (0°
corresponds to vertical assembly) is ideal. The SHM 30 is mounted in this way
to limit icicles and droplets falling from the mast of sensor from affecting the
real snow depth just below the sensor.
The sensor should also be pointed away from the mast. This avoids wind shield
or local thermal heating effects, which may be caused by the mast. Direct
sunlight may lead to an E15 or E17 error (see Section 9.1 Errors Codes) if
reflected sunlight from the snow surface hits the sensor.
Enusre that the assembly site will allow for measurements in undisturbed
conditions, and that local laser safety guidelines are fulfilled.
8
SHM 30 Snow Depth Sensor
6.1.1 Inclination Angle
The best measurement results are achieved with an inclination angle between
10-20°. To assist with achieving the proper inclination angle, part of the
mounting piece is a punched disk with a fixed 10° pattern allowing for fast,
easy installation.
If the mounting of the clamp to the mast cannot be precisely fixed or the mast
itself is crooked, the total inclination angle must be measured.
The inclination angle must be communicated to the SHM 30 using a terminal
program with the command ‘sp’. The sensor requires the ‘sp’ value to correct
the distance measurement.
Note
6.2
See Appendix A to calculate the correct inclination angle.
Mounting
The SHM 30 requires a suitable mast or crossbeam to be fixed to using one of
its mounting clamps. The typical angle of inclination of the mounting base
should be 10° or 20°.
Note
The SHM 30 should be fixed at a height of 2 – 5 m, on a suitable
mast.
Figure 6-1 Installation guide.
9
SHM 30 Snow Depth Sensor
6.2.1 Mounting Clamps
The SHM 30 is not shipped with mounting clamps. Figures 7-2 to 7-4
(inclusive) show three options of mounting clamps (including order number),
which can be ordered with the SHM 30.
Figure 6-2 8365.610-11 - standard for a Ø <72 mm mast
Figure 6-3 8365.608-11 specified for a mast with Ø 80 mm
Figure 6-4 8365.609-11 for masts upto Ø 300 mm
10
SHM 30 Snow Depth Sensor
Figure 6-5 Cable installation with mounting clamp 8365.610-11
Figure 6-6 Mounting clamp 8365.608-11 or 8365.609-11
6.3
Electrical Parameter
The SHM 30 has an identification plate where the electrical parameter and
single strands from the data cable are described. The standard data interface is
RS-232. Beside the digital interface output, an analog 4 mA – 20 mA current
output for snow depth measurements is available.
The snow depth sensor is connected by combined power and data cables. The
power supply is limited to values between 15 VDC and 24 VDC due to the
installed heating. This is necessary to operate the sensor within the specified
11
SHM 30 Snow Depth Sensor
temperature range. The less restricted voltage range without heating activities
is 10 - 30 VDC. It can be used for indoor tests or whenever the heater is
switched off manually.
6.4
Data Configuration and Communication
After the supply voltage is connected, the sensor starts automatically loading
the last parameter set. The factory defaults parameter set is used after the first
successful installation (shown in Table 6-1).
Table 6-1 lists the commands available during setup. In normal operating
mode, only a few parameters are needed for operating the snow depth sensor
(see Table 6-2, as an example).
Note
Commands can be entered in upper or lower case. All commands
must finish with <CR> <LF>; <CR> or <LF>.
6.4.1 Start Up
The autostart command ‘as’ defines the start up mode after the power is
connected. The preset value is ‘xm’ - the sensor starts automatically with a
snow depth measurement.
‘sry’/‘srn’ define either a message that is transferred after a measurement or the
sensor is waiting for a polling command.
After connecting the power for the first time, the distance between the sensor
and the surface is measured and a negative value is transmitted. The
transmitted snow depth value is calculated as follows:
Snow depth value = offset – measured distance
Table 6-1 Default Configuration Parameters
Command
Default
Description
asxm
XM
Sets ‘snow depth measurement mode’ ‘xm’ in
autostart ‘as’. Other options are: ‘id’, ‘lo’.
br
9600
Queries/sets baud rate.
ESC
$ 1B
Table
text
Interrupt measuring mode, ESC (Keyboard) or in
terminal window/script use HEX value $ 1B.
hf
4
Queries/turns Heater off
Heater will be switched off at 4°C. An increase
would lead to extended power consumption, but
may help stop the sensor from freezing in harsh
environments.
ho
2
Queries/turns Heater on
Heater will be turned on below 2°C. Decreasing
the temperature to -10°C is possible to save power.
Check to see if the output window is misting up or
starting to freeze.
id
12
Queries for sensor information.
SHM 30 Snow Depth Sensor
mr
mxd
of
Queries for all user memories 1-8. Sets one of the
eight, x=[1; 8], user memories with up to d=10
characters.
0
pa
Queries/sets offset, see ‘so’.
Queries for preset parameter values.
rb
-5
Queries/sets start value for analog current output.
Ex: 4 mA corresponds to 5 m.
re
5
Queries/sets end value for analog current output.
Ex: 20 mA corresponds to 5 m.
sda
sdb
Sda*
Message output in format a or b.
sf
1
Queries/sets scale factor. For example, change the
meter scale (sf=1) in a feet scale (sf=3.2808399).
After changing ‘sf’, other parameters such as ‘of’,
‘so’, and ‘xp’ are displayed in the revised scale
factor. The scale factor is limited in the range of sf
[0; 2000].
shd
10*
Queries/set signal for targets with high reflectivity
in 5 distances d=[a;e] (85% standard target). The
valid range for sh is 0<sh≤100.
sld
1*
Queries/sets signal for targets with low reflectivity
in 5 distances d=[a;e] (6% standard target). The
valid range for sl is: 0<sl≤100.
so
Measures the actual distance to the ground and
automatically defines a new offset (‘of’). The value
depends on ‘sp’. After changing ‘sp’, ‘so’ has to be
set again or ‘of’ has to be set manually.
sp
0.0
Queries/sets correction for the inclination angle in
degrees. 0° corresponds to a vertical downward
viewing sensor.
sr
sry
srn
SRN
sr: queries mode
sry: automatic mode
srn: polling mode
ss
6
Sets the signal strength thresehold value used to set
the snow flag in sdb message.
st
25
Queries/sets internal measuring time to
approximately 6.5 seconds; use this value for snow
depth measurements. For any other distance
measurement, the value may be set to 0 … 25.
xm
xp
Starts snow depth measurement.
10
Queries/sets maximum variation between two
running measurement values. Factory default is 10
m (sf=1) to allow for easy setup and to avoid any
E66 errors within the installation process. The
value can be modified. For example, 0.02 (2 cm if
13
SHM 30 Snow Depth Sensor
sf=1). A 2 cm variation in snow depth per minute
is a reasonable value.
Firmware 9.06 or newer: when a new measurement
is permanently out of tolerance (e.g. due to an
avalanche), E66 is reset after 60 measurements and
the current snow depth value is accepted as the
new value.
xt
30
xw
Queries/sets repetitions rate of measurement.
The default is every 30 seconds for a 6.25 second
long measurement. To test the sensor within the
configuration process, a 10 seconds or shorter time
interval is useful.
For short measuring periods (1 … 10 s), the
measurement time ‘st’ has be adjusted from st25 to
st={0 … 5}.
Queries (polls) for actual snow depth.
* The default value depends on the sensor type. See the product protocol
delivered with each sensor.
Table 6-2 Changing from automode ('sry') to polling mode ('srn')
Command
Description
ESC
$1B
Interrupt measuring mode
ESC (keyboard) or in terminal
window/script use
HEX value $1B
srn
Set polling mode
xm
Start measuring mode
Wait at least 6.5 seconds
xw
Poll for message
Wait for the next poll (at least the
time defined by ‘xt’ in seconds)
xw
Poll for message
To be able to configure the instrument, the serial interface RS-232 or RS-422
must be connected. Any terminal program can be used to set and query data.
Standard terminal programs include Hyper Terminal or Bray’s Terminal.
Standard configuration for the COM Port:
x
14
9600 Baud, 8N1, Handshake none
SHM 30 Snow Depth Sensor
Note
If the initialization of the serial port/message format is set
correctly, the sensor answers error codes E62 to E64.
The sensor status can be queried using the following commands:
x
x
Command ‘id’ shows sensor commands, software release, and serial
number (see Figure 6-7)
‘pa’ shows preset values (see Figure 6-8)
SHM 30, SN 080880, V 9.09
Measurement Commands:
XM[Enter].....................start measurement snow height
XW[Enter].....................display snow height and signal power
DM[Enter].....................distance measurement
DS[Enter].....................distance tracking 7m
DT[Enter].....................distance tracking
DW[Enter].....................distance tracking with cooperative target (10Hz)
Some useful commands:
LO[Enter].....................laser on
LF[Enter].....................laser off
MR[Enter].....................display all memory
SLd#[Enter]...................set reflectivity of dark target d=[a/b/c/d/e]
SHd#[Enter]...................set reflectivity of bright target d=[a/b/c/d/e]
SO[Enter].....................set current distance to offset (offset = - distance)
TP[Enter].....................internal temperature [°C]
Settings:
AS[Enter] / ASd[Enter]........display/set autostart command [DM/DS/DT/DW/TP/LO/ID/
XM]
BR[Enter] / BRx[Enter]........display/set baud rate [2400..38400]
HO[Enter] / HOx[Enter]........display/set temperature of heating on [-40°C ... +70°C]
HF[Enter] / HFx[Enter]........display/set temperature of heating off[-40°C ... +70°C]
Mx[Enter] / Mxd[Enter]........display/set memory x [1...8] [1 ... 10 ASCII-characters]
OF[Enter] / OFx.x[Enter]......display/set distance offset
RB[Enter] / RBx.x[Enter]......display/set distance of Iout=4mA
RE[Enter] / REx.x[Enter]......display/set distance of Iout=20mA
SA[Enter] / SAx[Enter]........display/set average value [1...20]
SD[Enter] / SDd[Enter]........display/set message format d=[a/b]
SE[Enter] / SEx[Enter]........display/set error mode [0/1/2]
0..Iout=const., ALARM=const.
1..Iout: 3mA @RE>RB, 21mA @RE<RB, ON@AH<0
2..Iout: 21mA @RE>RB, 3mA @RE<RB, OFF@AH<0
SF[Enter] / SFx.x[Enter]......display/set scale factor
SP[Enter] / SPx.x[Enter]......display/set tilt angle [0.0°...90.0°]
SR[Enter] / SRd[Enter]........display/set transmit result with each measurement [y/n]
ST[Enter] / STx[Enter]........display/set measure time [0...25]
XT[Enter] / XTx[Enter]........display/set measurement sequence [1 ... 600s]
XP[Enter] / XPx.x[Enter]......display/set max. allowed change in snow height between
two measurements
PA[Enter].....................display settings
PR[Enter].....................reset settings
Figure 6-7 ‘id’ for querying the list of commands
15
SHM 30 Snow Depth Sensor
autostart command[AS]..................xm
baud rate[BR]..........................9600
heating on[HO].........................2
heating off[HF]........................4
distance offset[OF]....................0
distance of Iout=4mA [RB]..............-5
distance of Iout=20mA [RE].............5
average value[SA]......................1
message format[SD]....................a
error mode[SE].........................1
scale factor[SF].......................1
tilt angle[SP].........................0
transmit result[SR]....................n
measure time[ST].......................25
reflectivity bright target A [SHA].....15.6695
reflectivity bright target B [SHB].....20.5645
reflectivity bright target C [SHC].....10.7353
reflectivity bright target D [SHD].....14.5077
reflectivity bright target E [SHE].....4.14621
reflectivity dark target A [SLA].......0.729548
reflectivity dark target B [SLB].......1.56198
reflectivity dark target C [SLC].......1.09263
reflectivity dark target D [SLD].......1.4683
reflectivity dark target E [SLE].......0.428003
measurement sequence[XT]...............59
max change between 2 measurements[XP]..10
memory 1 [M1]..........................
memory 2 [M2]..........................
memory 3 [M3]..........................
memory 4 [M4]..........................
memory 5 [M5]..........................
memory 6 [M6]..........................
memory 7 [M7]..........................
memory 8 [M8]..........................
Figure 6-8 'pa' example output for a parameter set in Firmware 9.09
6.5
Special Values for EEE.EEEE in Case of Errors
In case of errors (Table 8-1) the last valid measurement is repeated as the
eee.eeee value, while an ‘E’ error code indicates whether the given value is
usable or not. Directly after ‘xm’ start command eee.eeee contains its
initialization values as follows:
eee.eeee :=rb (start value of range) (firmware 9.06, consistent with I out.
eee.eeee := 0 m (only firmware 9.05)
eee.eeee :=-99 m (firmware 9.04 and earlier)
16
SHM 30 Snow Depth Sensor
6.6
Analog Output
In the analog output mode, measured values are transformed to a 4 … 20 mA
current level. The parameter RE and RB in Table 6-1 define the distances of
the 4 … 20 mA interval.
஽௜௦௧Ǥିோ஻
ܴ‫ ܧ‬൐ ܴ‫ܤ‬ǣ ‫ݐݑ݋ܫ‬ሺ݉‫ܣ‬ሻ ൌ Ͷ݉‫ ܣ‬൅ ͳ͸ ‫ כ‬ቀ
ோாିோ஻
ܴ‫ ܤ‬൐ ܴ‫ܧ‬ǣ ‫ݐݑ݋ܫ‬ሺ݉‫ܣ‬ሻ ൌ ʹͲ݉‫ ܣ‬െ ͳ͸ ‫ כ‬൬
ቁ ݉‫ܣ‬
‫ݐݏ݅ܦ‬Ǥ െܴ‫ܧ‬
൰ ݉‫ܣ‬
ܴ‫ ܤ‬െ ܴ‫ܧ‬
Error messages are transformed to 3 mA (RE>RB), or 21 mA (RB>RE).
6.7
Signal Strength (Signal Intensity)
The normalized signal strength value SN or SS is submitted at the second
position in the data message using the format ‘sss.sss’. SN (SS) are calculated
from the measured signal strength value SM. The SM measurement is performed
independently after a snow depth measurement and takes approximately 0.5 s,
which corresponds to an average of about 10 single frequency measurements. It
may be possible that the snow depth measurement has been stopped due to an
error caused by too much background light, while the signal strength value is
still transmitted.
Since Firmware 9.05 SS is defined as the normalized signal intensity value. The
normalization process was been performed on a standard target 15 m in the
distance. The normalized signal strength value S S should be comparable
between different sensors in the 0.5 range for dark targets and 10 for bright
targets.
This procedure was not precise enough to use the signal strength value for
threshold methods like snow/no snow independent from the distance, because
of the distance dependency. As a result, the number of distances used for
reference targets are extended to 5. Firmware 9.09 supports these new settings
first. Additionally, a set of standard targets with 6.25% and 86% reflectivity is
introduced to allow field checks of the sensor. Instead of S S the new signal
strength value SN is used.
The normalization of the signal strength value is done within the test procedure
for each sensor at the Jenoptik factory. The normalization parameters SLd
(signal strength on black target) and SHd (signal strength on white target) are
saved for the 5 distances d in the sensor flash memory and are also written in
the test report handed out with each instrument.
ܵௌ ൌ ͳͲ െ ሺͲǡ ͷሻ
‫ כ‬ሺܵெ െ ܵ‫ܮ‬ሻ ൅ Ͳǡ ͷ
ܵ‫ ܪ‬െ ܵ‫ܮ‬
ܵே ሺ‫ݔ‬ሻ ൌ ͻ ‫ כ‬
ܵெ െ ܵ‫ܮ‬ሺ‫ݔ‬ሻ
൅ͳ
ܵ‫ܪ‬ሺ‫ݔ‬ሻ െ ܵ‫ܮ‬ሺ‫ݔ‬ሻ
17
SHM 30 Snow Depth Sensor
To be able to calculate SN(x), the signal strength values –SL(x) and SH(x), in
measured distance – must first be determined from the reference points. For
example, the calculation process is listed here for the special cases that the
measured distance is between the reference points a and b.
ܵ‫ܪ‬ሺ‫ݔ‬ሻ ൌ ܵ‫ ܽܪ‬൅ ሺ݄ܾܵ െ ܵ‫ܽܪ‬ሻ
‫ כ‬ሺ‫ ݔ‬െ ܽሻ
ܾെܽ
The calculation of SN is only valid when the measuring distance is known,
meaning tha the signal strength SN cannot be delivered in comparison to SS,
when the distance measurement cannot be achieved.
Note
Users may change the SH and SL values to meet their specific
needs.
6.7.1 Other Corrections
The signal strength depends on the sensor temperature. In cases of snow depth
measurements, the relevant temperate range is small. In some cases, the signal
strength should be used in large temperature ranges, compensation is useful.
Initial measurements indicate the following dependency for targets with
reflectivites >80:
ܵே ሺܶሻ ൌ െͲǤͳʹͷ‫ܶݔ‬ሺԨሻ ൅ ܵே ሺʹͶԨሻ ൅ ͵
At zero degrees, this correction leads to an increase of signal strength by 3.
6.8
SF in Analog Mode
Only in Firmware 9.05, the analog mode is not correctly displayed for SF്1. If
other scale factors have to be used, RE and RB have to be modified, as shown
in the following typical example:
RB = -1 m; RE = 4; SF = 1: okay
For SF=2: set RB=-2 and RE=8, enter SF=-2
18
SHM 30 Snow Depth Sensor
6.9
Wiring
Table 6-3 Wiring
Color Code
8 wire
interface
cable
SHM 30
Connection
Pin on 12-pole
binder connection
Pink
Power
Power Supply +24V
G
Grey
Power
Gnd
Power Supply Gnd
J
Green
Transmit –
Tx
Datalogger Rx
(C2/C4… or
U2/U4…)
A
Yellow
Receive –
Rx
Datalogger Tx
(C1/C3… or
U1/U3…)
B
Brown
Heater
On/Off
Datalogger 12V
E
White
Not used
No connection
F
Blue
RS-232
Gnd,
Iout Gnd
Datalogger G
L
Red
Iout
No connection
D
6.10 CR1000 Programming Example
'CR1000 Series Datalogger
'Program to read data from SHM30 Snow Depth sensor
SequentialMode
'---------------------------------------------------------------------------------------------------------------------'Diagnostic variables
'---------------------------------------------------------------------------------------------------------------------Public PTemp, batt_volt
Units PTemp = deg C
Units batt_volt = volts
'---------------------------------------------------------------------------------------------------------------------' Variables for SHM30
'---------------------------------------------------------------------------------------------------------------------Public SHM30_data(4)
19
SHM 30 Snow Depth Sensor
Alias SHM30_data(1) = SHM30_SnowDepth
Units SHM30_SnowDepth = m
Alias SHM30_data(2) = SHM30_SignalStrength
Alias SHM30_data(3) = SHM30_Temp
Units SHM30_Temp = deg C
Alias SHM30_data(4) = SHM30_ErrorCode
Dim inputString As String * 64 'String to hold data string received from SHM30
Dim NBytesReturned
Dim shm30Check As Long 'Calculated checksum
'---------------------------------------------------------------------------------------------------------------------'Wiring for SHM30
'---------------------------------------------------------------------------------------------------------------------Const SHM30port = COM1 'Communications port used for connection to SHM30
'Pink
Power Supply 24V
'Grey
Power Supply G
'Green
CR1000 C2
'Yellow
CR1000 C1
'Blue
CR1000 G
'Brown
CR1000 12V
'---------------------------------------------------------------------------------------------------------------------'Diagnostic data table
'---------------------------------------------------------------------------------------------------------------------DataTable (Diagnostic,1,-1) 'Set table size to # of records, or -1 to autoallocate.
DataInterval (0,24,Hr,10)
Minimum (1,batt_volt,FP2,0,False)
Maximum(1,batt_volt,FP2,0,False)
Maximum (1,PTemp,FP2,False,False)
Minimum (1,PTemp,FP2,False,False)
EndTable
'---------------------------------------------------------------------------------------------------------------------'Snow depth data table
'---------------------------------------------------------------------------------------------------------------------DataTable(HourlySnowDepth,1,-1)
DataInterval(0,1,hr,10)
Average(1,SHM30_SnowDepth,FP2,false)
EndTable
'Main Program
BeginProg
'Open COM port for SHM30
SerialOpen (SHM30port,9600,3,0,200)
'Set up SHM30 for polled mode
SerialOut (SHM30port,CHR(&h1B),"",1,10)
SerialOut (SHM30port,"srn" & CHR(13),"",1,10)
Scan (15,Sec,0,0)
PanelTemp (PTemp,_60Hz)
Battery (batt_volt)
'Measure SHM30 once every 15 minutes
If TimeIntoInterval(0,15,min) Then
'Send the measurement command
SerialOut (SHM30port,"xm" & CHR(13),"",1,0)
'Wait for the sensor to make its measurement
Delay (1,6500,mSec)
'Request the data from the sensor
SerialOut (SHM30port,"xw" & CHR(13),"",1,0)
20
SHM 30 Snow Depth Sensor
Delay(1,100,msec)
'Receive the data from the sensor
SerialInRecord (SHM30port,inputString,ASCII(">"),0,ASCII("<"),NBytesReturned,01)
'Verify the checksum to ensure the sensor's response is valid
shm30Check = CheckSum (inputString,7,0 )
If shm30Check = 0 Then
SplitStr (SHM30_data(),inputString,"",4,0) 'If checksum good, extract values from
string
Else 'If chesksum
SHM30_data(1) =
SHM30_data(2) =
SHM30_data(3) =
SHM30_data(4) =
EndIf
EndIf
fails, write NAN to variables
NAN
NAN
NAN
NAN
CallTable Diagnostic
CallTable HourlySnowDepth
NextScan
EndProg
7.
Maintenance
Note
Avoid looking directly into the laser beam.
TABLE 7-1. Cleaning Schedule and Action
Interval
Cleaning Required
Supplies required
Quarterly
Ensure the beam path is clean.
Remove sediment, dust, and insects
from the mechanical parts.
*Microfiber wipes
*Neutral cleaning
agent
*Air pressure for
insects in the optical
tube
Annually
(Before
winter)
Check cable connector and mounting
clamps. Clean stray light protection
tube.
*Allen key
*Microfiber wipes
*Neutral cleaning
agent
*Air pressure for
insects in the optical
tube
(See Figures 8-1 to 83)
As
required
Remove snow and ice.
21
SHM 30 Snow Depth Sensor
Note
Do not attempt to clean the optical components in the field.
Remove the sensor, by unscrewing the tube and aperature in front
of the sensor to clean the optical components properly.
Figure 7-1 Unscrew the tube for stray light reduction to clean the
mechanics and optics.
Figure 7-2 Cleaning supplies: bellows, Allen key (T handle), and tube with
aperature.
22
SHM 30 Snow Depth Sensor
Figure 7-3 Core sensor module LDM30.11. In case of service, only these
core components need to be exchanged in the field.
If it is necessary to exchange the measuring module, only the core module
(shown in Figure 8-3) should be sent to Campbell Scientific (Canada) for
repair.
8.
Troubleshooting
8.1
Error Codes
The SHM 30 has several built-in error codes. The error codes are available if
the sensor is connected to the RS-232 or RS-422 digital interfaces. The analog
current output generates only a 3 mA (or 21 mA) current to indicate an error
without further details.
In normal operating mode, the E15 to E24 errors indicate problems in running
temperatures. E61, E65, and E67 may occur if the user communicates with the
measurement.
In the event of hardware errors, the SHM 30 requires service.
23
SHM 30 Snow Depth Sensor
TABLE 8-1. Error Codes
24
Error Codes
Description
E15
Signal is too weak or distance is too short (<10 cm)
E16
Signal is too strong (relection from mirrors)
E17
Background light error
E18, E19
DX mode only (industrial sensor error – not used for SHM)
E23
Temperature below -10°C
E24
Temperature above +60°C
E31
Hardware error – faulty EEPROM. Return sensor for repair.
E51
APD voltage value failure (straylight of hardware error)
E52
Laser current is too high. Possibly a broken laser diode.
E53
Math (division by zero)
E54, E55
Hardware errors. Return sensor for repair.
E61
Invalid command in the RS-232 or RS-422 configuration
E62
1. Hardware error in the interface
2. Incorrect value in the interface communication (parity
error S10)
E63
S10 overflow – check time for emitted signals in application
software
E64
Framing error S10 – serial interface parameter not set
correctly to 8N1
E65
Measurement was interrupted by a query from the user.
Since firmware 9.05 this error no longer occurs if the
running measurement is queried by a xw in polling mode.
The result is transmitted once the measurement is complete.
E66
The variation of snow depth between 2 consecutive
measurements is outside the limit set by xp. Instead, the last
valid value is transmitted.
Firmware 9.06 – after 60 measurements, the new value is
accepted.
E67
Measurment was interrupted by the ‘ESC’ command
SHM 30 Snow Depth Sensor
TABLE 8-2. Message Responses and Analog Feedback for Error Codes
Note
Error
Codes
RS-232/RS-422 Message
Responses
Iout (current value 3…21
mA)
E15
>eee.eeee sss.sss TTT 15 P<
3, 21 mA
E16
>eee.eeee sss.sss TTT 16 P<
3, 21 mA
E17
>eee.eeee sss.sss TTT 17 P<
3, 21 mA
E23
>eee.eeee sss.sss TTT 23 P<
3, 21 mA
E24
>eee.eeee sss.sss TTT 24 P<
3, 21 mA
E31
E31
3, 21 mA (firmware 9.06)
last value (firmware 9.01 –
9.05)
E51
>eee.eeee sss.sss TTT 51 P<
3, 21 mA
E52
>eee.eeee sss.sss TTT 52 P<
3, 21 mA
E53
>eee.eeee sss.sss TTT 53 P<
3, 21 mA
E54, 55
>eee.eeee sss.sss TTT 54 P<
3, 21 mA
E61
E61
Last value
E62, E63,
E64
E62, E63, E64
Last value
E65
>eee.eeee sss.sss TTT 65 P<
4 mA (firmware 9.06)
last value (firmware 9.02 –
9.05)
E66
>eee.eeee sss.sss TTT 66 P<
3, 21 mA (firmware 9.06)
last value (firmware 9.02 –
9.05)
E67
E67
4 mA (firmware 9.06)
last value (firmware 9.05)
Iout {3; 21} depends upon the re, rb settings
8.1.1 Start up Error Responses
The following snow depth values are initialization values that will be
transmitted in the data message. Whenever an error is detected immediately
upon system start-up or whenever the xm start command is set, an error occurs:
eee.eeee := RB (start value of range) (firmware 9.06, consistent with Iout)
eee.eeee := 0 m (only firmware 9.05)
eee.eeee :=-99 m (firmware 9.04 and earlier)
Note
In other cases, the last valid measurement is repeated as eee.eeee.
25
Appendix A. Determining the Correct
Inclination Angle
A.1 Reference Object Technique
The installer can use a reference object with a specified height c to determine
the angle of inclination.
1. Stop measuring process (Esc) and change the measuring time interval to
“xt10” to 10 seconds.
Set: “sp0” amd “of0”.
Ensure that “sf” is set up correctly and xp allowd for a high variability for the
installation process.
Ex: if sf = 1, xp > c.
2. Mount the sensor at the desired angle position (ex.: 15°) and perform 1
distance measurement.
3. Start measurement ‘xm’. Wait 6 seconds. Press ‘xw’ in polling mode to
query distance value.
4. Stop measurement (Esc) and note the distance.
5. Place object (B) and perform a new measurement.
6. Calculate angle α (C) and use the ‘sp’ command to set the anlge.
7. The measured distance values now correspond to the vertical distance. You
will receive a negative value.
8. Perform offset measurement ‘so’.
9. Change :
‘xt’ to the final time interval
‘xp’ to the final variability
10. Restart the measurement process with ‘xm’.
A-1
Appendix Title
A
x1
C
Calculation of the installation angle:
D
c
x1 – x2
D
Y c
,
$x1 ,
Example: x1= 4.38 m, x2 = 3.8 m, c = 0.5 m
D= 30.5°
Figure 8-1 Technique for determining the angle of inclination
A.1.1 Absolute and Relative Error
If the height of the reference object c is not well-defined, the corresponding
error in a leads to a 1:1 error in the measured distance between the sensor and
the surface. Even if the relative error between two snow depth measurements is
much smaller, it is worthwhile to use precise reference object.
A-2
SHM 30 Snow Depth Sensor
A.2 Plumb Method
Using a perpendicular is a more precise method for determining the inclination
angle of the sensor.
1. Mark the position of the perpendicular at the ground and measure the
distance y at ground level to the laser spot.
2. Use the distance measured by the sensor (sp0, of0) and y to calculate correct
angle of inclination.
Figure 8-2 Plumb procedure: ɑ = arcsin (y/ x1)
A-3
Appendix B. Firmware Release
Table 8-3 Firmware Releases
Date
Firmware
Release
Description
01.06.2009
9.04
Official market launch of SHM 30 in August
2009 with Firmware 9.04.
01.09.2011
9.05
* angle precision ‘sp’ corrected by a factor of 10
from 1° to 1.0°.
* normal reflectivity integrated (factory
calibration to white ‘sh’ and black ‘sl’ targets).
* output resolution modified from 1 mm to 0.1
mm.
* Bug in message display solved for higher scale
factor values.
* Error 65 will no longer appear if measurement
is interrupted by polling command.
Measurement will now be finalized and the
answer will be sent upon completion.
*E67 added – appears when a measurement has
been stopped by ESC command.
15.11.2011
9.06
* Error handling for E66 (‘xp’ out of range)
changed. New value is accepted after 60
measurements. Analog current mode shows 3
mA/21 mA instead of last value.
09.07.2012
9.07
* 2 bugs have been fixed – in rare cases they
lead to a frozen state in polling mode.
* Commands can be entered in upper or lower
case.
* DMA – transfer will no longer be interrupted
by measuring process.
1.11.2012
9.08
* Format for single digit temperature values in
message corrected:
Previously: TTT <space>+9
Now: TTT+09
* ‘sh’ and ‘sl’ are now limited [0, 100].
15.7.2013
9.09
* Message 2 (‘sdb’) added.
* User variables M1 to M8 were added.
* Normalization signal strength was revised.
* ‘sld’ and ‘shd’ parameters were introduced.
*Variable snow flag and threshold ‘ss’ were
implemented.
B-1
B-1
Campbell Scientific (Canada) Corp. | 14532 131 Avenue NW | Edmonton AB T5L 4X4 | 780.454.2505 | www.campbellsci.ca
AUSTRALIA | BRAZIL | CANADA | COSTA RICA | FRANCE | GERMANY | SOUTH AFRICA | SPAIN | UNITED KINGDOM | USA
">