Lufft ARS31-UMB User manual

www.lufft.com
Operating Manual ARS31-UMB
Active Road Sensor
Order No.: 8610 U050 50m cable
Version V5 (10/2012)

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 2
Contents
1Please read before commissioning ........................................................................................................3
1.1 Symbols used.....................................................................................................................................3
1.2 Safety instructions ..............................................................................................................................3
1.3 Designated use...................................................................................................................................3
1.4 Guarantee...........................................................................................................................................3
1.5 Incorrect use.......................................................................................................................................3
1.6 Nomenclature .....................................................................................................................................3
2Device description ..................................................................................................................................4
2.1 Method of operation............................................................................................................................4
2.2 Availability of measurement values....................................................................................................5
3Installation...............................................................................................................................................6
3.1 Preparation.........................................................................................................................................6
3.2 Installation...........................................................................................................................................6
3.3 Connecting the cable..........................................................................................................................7
3.4 Commissioning and testing ................................................................................................................9
4Maintenance.........................................................................................................................................10
4.1 Replacing the sensor system ...........................................................................................................10
4.2 Connections......................................................................................................................................11
5Configuration ........................................................................................................................................12
5.1 Factory settings ................................................................................................................................12
5.2 Using PC configuration software......................................................................................................12
5.3 Firmware update...............................................................................................................................14
6Communication.....................................................................................................................................15
6.1 Binary protocol..................................................................................................................................15
6.2 ASCII protocol...................................................................................................................................17
6.3 Channel assignment for the data request ........................................................................................18
6.4 Mapping standards...........................................................................................................................20
7Technical data ......................................................................................................................................21
7.1 Measurements..................................................................................................................................21
7.2 Storage conditions (complete sensor)..............................................................................................21
7.3 Operating conditions.........................................................................................................................21
7.4 Electrical data...................................................................................................................................21
7.5 Interfaces..........................................................................................................................................22
7.6 Mechanical data (excluding cable)...................................................................................................22
8EC Certificate of Conformity.................................................................................................................23
9Troubleshooting....................................................................................................................................24
10 Service and maintenance.....................................................................................................................25
11 Disposal................................................................................................................................................25
12 Manufacturer.........................................................................................................................................26
12.1 Technical support .............................................................................................................................26
Version history:
Version
Date
Edited by
Comments
V1.0
17.10.2008
LA/BR/FS
First version
V1.01
02.02.2009
FS
Accuracy freezing temp. / cable length / power consumption
V1.3
25.02.2009
LA/FS/BR
Adaption to actual firmware
V2
16.12.2010
BR/FS
Adaption to actual firmware, explanation ”saline concentration”
V3
14.06.2011
BR/LA
Adaption to actual firmware, smoothing operator for FT
V4
30.08.2011
BR/LA
Channel assignment, availability of measurement values
V5
08.10.2012
LA/BR/FS
Adaption to actual device version and actual standards

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 3
1 Please read before commissioning
Before using the equipment, please read the operating manual carefully and follow the
instructions in every detail.
1.1 Symbols used
Important indication concerning possible hazards to the user
Important indication for the correct functioning of the equipment
1.2 Safety instructions
Installation and commissioning must only be carried out by suitably qualified specialist
personnel.
Never take measurements on or touch live electrical parts.
Pay attention to the technical data and storage and operating conditions.
1.3 Designated use
The equipment must only be operated within the range of the specified technical data.
The equipment must only be used under the conditions and for the purposes for which
it was designed.
The safety and operation of the equipment can no longer be guaranteed if it is modified
or adapted.
Do not continue to use equipment that is obviously defective.
1.4 Guarantee
The guarantee period is 12 months from the date of delivery. The guarantee is forfeited if
the designated use is violated.
1.5 Incorrect use
If the equipment is installed incorrectly
-It may not function
-It may be permanently damaged
If the equipment is not connected correctly
-It may not function
-It may be permanently damaged
-There may be a possibility of an electrical shock
1.6 Nomenclature
Tg: Freezing temperature that the sensor identified
Tu: Road surface temperature, ambient temperature

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 4
2 Device description
Active Road Sensor ARS31-UMB serves to determine the freezing temperature of a liquid
on the road surface. It can be used to measure the following data:
Salt concentration (NaCl, CaCl and MgCl)
Product concentration (potassium acetate, potassium)
Freezing temperature (independent of mixture)
The sensor excels further due to the following features:
Compact design and easy installation
Low maintenance
Parts can be replaced without uninstalling the device
Data transfer via RS485
Internal electrical isolation of power supply
ESD protection on all interfaces
Input voltage range 9V...36V
Inverse-polarity protection
2.1 Method of operation
ARS31-UMB determines the freezing temperature of a liquid on the road surface by means
of active cooling and heating. ARS31-UMB allows precise determination of the freezing
temperature in the absence of accurate knowledge of the type or mixture of salt.
The sensor operates in a temperature range described in the chapter 7.3 Operating
conditions.
The freezing temperature is calculated for road surface temperatures of less than 5°C
(adjustable between 2°C and 10°C). The lowest possible freezing temperature that can be
calculated is about 20°C below the current road surface temperature, for details see
chapter 7.1.1 Freezing temperature.
The sampling rate for freezing point measurement in the sensor is configurable and may
be set to 20, 30 or 60 minutes (factory settings: 20 minutes).
To avoid measurement gaps due to interference during measurement, the sensor is
equipped with an intelligent “hold measurement” function for freezing temperature.
If there is no freezing temperature / salt concentration detected in a measuring cycle the
last identified freezing temperature will be delivered for the following 40 minutes (default:
40 –interval can be adjusted). During this interval the freezing temperature can only move
to 0°C if the sensor definitely detects clear water on the road.
The freezing temperature profile is smoothed by the sensor. This function can be disabled
using the UMB-Config Tool.
Data polling takes place through any desired host computer which supports any of the
communication protocols described in Section 6 and disposes of an RS485 interface.

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 5
Measurements are polled and transmitted over an RS485 interface.
The device is connected using a 4-core cable.
Windows PC software is available for configuration and measurement polling during
commissioning.
2.2 Availability of measurement values
After a successful measurement, the measurement values are available for query until new
measurement values are available. Synchronization between query and measurement
cycle is not needed. It is recommended to poll the sensor every minute. Within the
measurement interval the measured values are immediately updated when they become
available. Due to different environmental conditions the timing of the availability of
measurements can alter in the measurement interval, the measurement values are
therefore not necessarily updated in the grid of the selected measurement interval.
Example: Measurement interval 20 minutes
Start measurement
Start measurement
Start measurement
Start
TG 1
availa
ble
TG 2 available
TG 3
availa
ble
0
min
5
min
10
min
15
min
20
min
25
min
30
min
35
min
40
min
45
min
50
min
55
min
60
min
1) At time 15 min TG 1 is available and will be issued
2) In the next measurement cycle, at the time 25 min GT 2 is determined and issued. So
TG1 was issued for 10 minutes.
3) In the next measurement cycle, at the time 25 min GT 3 determined and issued. So TG2
was issued for 30 minutes.

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 6
3 Installation
The road sensor is installed in the middle of the carriageway. If the road has two lanes, the
sensor is installed in the left hand lane.
3.1 Preparation
The sensor requires a hole of diameter Dm > 16 cm and depth Dp = 6 cm. A slit of width
W = 2 cm and depth Dp = 5 cm is cut into the road for the cable.
Attention! When installing on bridges, make sure that the insulation layer is not
damaged (it is not always possible to maintain a depth of 6 cm in these cases).
3.2 Installation
Warning: Do not undo the cable connections under any circumstances
You can only cut the cable at the control panel end.
The cable must be laid in a protective tube in such a way as to ensure that any expansion
of the road covering does not affect the cable. The road sensor cables must not be
subjected to tensile force during installation.
Warning: Damage to the cable sheath or external sensors causes water ingress into
the sensor. Sensors with damaged cables must not be installed and can only be
repaired by Lufft.
Install the road sensor in the hole provided in such a way that it is flush with the road
surface. To do this, place the installation aid - which is already mounted on delivery - on
the road surface. It may be necessary to align the sensor by bending the installation aid.
Under no circumstances must the road sensor project beyond the surface of the
road covering (damage due to snow-clearers).
Fill the cavities with casting resin concrete.
Only use concrete bedding systems whose temperature remains below 80°C on
hardening as otherwise the road sensor will be damaged.
After the casting resin concrete has hardened, remove the installation aid and the green
protective film. Reinstall the fixing screws of the installation aid in the open holes of the
sensor (torque 2 Nm).
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Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 7
3.3 Connecting the cable
The road sensor cable is connected in the control panel together with the power supply
and the bus system, e.g. ISOCON-UMB.
The screening of the connection cable MUST be laid to ground.
Connection to the road sensor cable:
Brown Positive power supply
White Negative power supply
Green RS485_A
Yellow RS485_B
Illustration 1: ISOCON-UMB connection
Warning! Connecting the cables incorrectly will destroy the road sensor!
Illustration 2: Installation of ARS31-UMB in the road

Sensor voltage output 24 V
ARS31 sensor interface


Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 8
Illustration 3: Installing the ARS31-UMB

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G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 9
3.4 Commissioning and testing
After the device has been installed and connected correctly, the ARS31-UMB is initialized
and measurement begins. The first measurements are available after approximately 1
minute; after approximately 20 minutes, the measurements for freezing temperature and
saline concentration are available (provided that the ambient conditions allow such
measurements).
The functionality of the road sensor must be checked after it has been installed. The
sensor must be connected to an evaluation unit (e.g. PC with UMB-Config Tool) for this
purpose. Communication between sensor and evaluation unit must be checked for perfect
operation.

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 10
4 Maintenance
Maintenance should be carried out on the road sensor once annually. This includes the
visual inspection of the housing. It is recommended to clean the surface of the sensor if it
is heavily soiled. Sensor replacement is recommended in the event of significant
mechanical damage to the sensor. This also applies if the sensor’s plastic insert is
severely worn.
4.1 Replacing the sensor system
If the road sensor’s plastic insert becomes unusable due to mechanical effects, or the
sensor is damaged, the plastic insert can be replaced with no need to replace the entire
housing.
Attention: Only replace the sensor system when the road is dry
To uninstall the plastic insert, remove all six hexagon socket head screws. There is a small
opening on the edge of the cover suitable for inserting a screwdriver. This allows you to lift
out the plastic insert. Make sure that the connection cable on the underside of the sensor
has not broken off. The connectors must be pulled out without putting a strain on the cable.
The housing must be cleaned thoroughly before installing the new sensor. Even small
impurities on the seat of the seal can cause the sensor to fail in the long term. No moisture
must be trapped in the housing!
On connecting the connector to the new sensor, make sure that you do not touch the
sensor electronics. Electrostatic discharge (ESD) destroys the sensor.
The seal must be greased with silicone grease prior to insertion. The seal must not bend
out of line on installing the plastic cover. You should also make sure that the thermal
conducting foil on the under edge of the housing is not displaced during installation. The
plastic cover must be inserted into the housing without the use of force. There is only one
possible installation position: The apertures on the copper head of the sensor must
point in the direction of the cable glands on the housing. The threads of the fixing screws
must be greased. First the screws are attached loosely and then tightened cross-wise
(torque 2 Nm).
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Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 11
4.2 Connections
4.2.1 Cable
See Section 3.3 Installation –Connecting the cable
4.2.1.1 Power supply
The ARS31-UMB power supply is 24DC (9.... 36V VDC). The power supply unit used must
be approved for operating devices of protection class III (SELV).
4.2.1.2 RS485 interface
The device has a half-duplex, 2-wire RS485 interface with the following settings:
Data bits: 8
Stop bit: 1
Parity: none
Adjustable baud rates: 1200, 2400, 9600, 19200, 38400 (standard: 19200 bit/s)
Please do not change the baud rate of the sensor unless it is absolutely essential. If
the sensor is operated via ISOCON-UMB, the baud rate of the sensor must match the
set baud rate on the ISOCON-UMB.
The screened cable MUST be laid to ground in the control cabinet
If the device is not connected properly:
-It may not function correctly
-It may be permanently damaged
-There is a danger of electric shock under certain circumstances
4.2.2 Connections in the housing
There is a single 4-pole terminal block on the underside of the plastic insert. This serves to
connect the power supply and the interface to the associated cable.
Power supply connection assignment/RS485:
Pin
Assignment
1
GND
white
2
V+, 24 V
brown
3
A (Rx+)
green
4
B (Rx-)
yellow
The data and power supply cables are connected via a 4-pole terminal block. Cable type
LI-2YCYv2X2X0.5 is used.
Cable labeling on the pins is based on DIN 47100.
The screened cable must be laid to the ground circuit connector in the control panel.
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Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 12
5 Configuration
Lufft provides PC software for configuration purposes. Using this software, the user can
adjust the sensor according to his needs.
Starting from Firmware V10.0 for ARS31-UMB the UMB-Config Tool version 1.7.3 or
newer must be used.
5.1 Factory settings
The factory settings of the ARS31-UMB are as follows:
Device ID: 1
Class ID 4
Baud rate: 19200
RS485 protocol: binary
5.2 Using PC configuration software
The main functions of the configuration software are described in detail in the Online Help.
For this reason only the sensor-specific menus and functions are described here.
5.2.1 Configuration
After loading an ARS31-UMB configuration, all relevant settings and values can be
adjusted.
If several ARS31-UMB devices are operated on a UMB network, the ID must be changed
before connection to the network, as each device requires a unique ID. IDs are allocated in
ascending order, beginning with number one.
The measuring rate indicates how often a new measuring cycle is started. This value is
configurable and can be set to 20, 30 or 60 minutes (factory settings: 20 min.)
If there is no freezing temperature / salt concentration detected in a measuring cycle the
last identified freezing temperature will be delivered for the following 40 minutes (default:
40 –interval can be adjusted). During this interval the freezing temperature can only move
to 0 if the sensor definitely detects clear water on the road. The interval for maintaining the
freezing temperature can be configured in the UMB-Config-Tool and can adopt values
between 20 and 120 minutes (default 40 minutes). The function can be deactivated by
unticking the option “FT data hold active”.
With the option "FT smoothing operator active", a smoothing function for the freezing
temperature can be activated. The operator itself can be set between 0 (maximum
smoothing, no change in the FT) and 100 (no smoothing). After activating this function a
start value of 40 is set for the smoothing operator. This value can be adjusted if necessary.
Freezing temperature is detected when road temperatures are lower than the road
temperature threshold. If the road temperature is higher than this threshold, freezing
temperature is not detected. The threshold value is adjustable between 2°C and 10°C.
The dry threshold defines the measured value on the ARS31-UMB from which a dry road
is assumed and the freezing temperature is no longer measured.
If this value is too high, the ARS31-UMB measures during dry conditions, which may lead
to incorrect measurements caused by condensation on the sensor element.
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Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 13
In the UMB-Config-Tool the temperature limit of the freezing temperature can be adjusted
if necessary (factory setting: 0, this means no limit for freezing temperature).
After the activation of the freezing temperature limit, the smoothed freezing temperature
can be transitional-wise under the temperature limit (if the freezing temperature directly
before the change was under the opposed limit).
5.2.2 Measurement polling channels
You can activate the measurement polling channels for the UMB-Config-Tool by clicking
on the respective channel. This setup has no influence on the channels which can be
queried by the user software.

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 14
5.3 Firmware update
The description of the firmware update can be found in the instructions for the UMB
configuration tool.
New firmware is uploaded via the RS485 interface. It is not necessary to open the housing
for this purpose. However, firmware uploads must take place at a temperature between 0
and 60°C. The update is controlled by means of PC software.

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 15
6 Communication
Communication takes place with the ARS31-UMB over a 2-wire half-duplex RS485
interface with the aid of the ISOCON-UMB. The bus is not terminated with a resistor due to
dissipation in the ARS31-UMB. The use of PC software from Lufft for purposes of
maintenance and diagnosis makes an RS485-RS232 or RS485-USB converter
superfluous.
The protocol is based on meteorological sensor communications protocol. This contains
bus-compatible binary protocol which requires a strict master-slave principle and is
enabled on delivery. The ARS31-UMB is a slave and only responds to requests. AN ASCII
protocol is available for rudimentary measurement polling only.
Depending on the device configuration, the calculated freezing point can be requested in
binary or ASCII protocol.
6.1 Binary protocol
This operating manual only includes one example of an online data request. Please refer
to the current version of the document Communications Protocol for Meteorological
Sensors (UMB protocol) for details of the mode of operation.
6.1.1 Framing
The data frame is constructed as follows:
1
2
3 - 4
5 - 6
7
8
9
10
11 ... (8 + len)
optional
9 + len
10 + len
11 + len
12 + len
SOH
<ver>
<to>
<from>
<len>
STX
<cmd>
<verc>
<payload>
ETX
<cs>
EOT
SOH Control character for the start of a frame (01h) 1 byte
<ver> Header version number, e.g.: V 1.0 <ver> = 10h = 16d; 1 byte
<to> Receiver address, 2 bytes
<from> Sender address, 2 bytes
<len> Number of data bytes between STX and ETX; 1 byte
STX Control character for the start of payload data transmission (02h); 1 byte
<cmd> Command; 1 byte
<verc> Version number of the command; 1 byte
<payload> Data bytes; 0 –210 bytes
ETX Control character for the end of payload data transmission (03h); 1 byte
<cs> Checksum, 16 bit CRC; 2 bytes
EOT Control character for the end of the frame (04h); 1 byte
Control character: SOH (01h), STX (02h), ETX (03h), EOT (04h).
6.1.2 Addressing of class and device ID
Addressing takes place using a 16 bit address. This is divided into sensor class ID and
device ID.

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 16
Address (2 bytes = 16 bits)
Bits 15 –12 (top 4 bits)
Bits 11 –0 (bottom 12 bits)
Class ID (0 to 15)
Device ID (0 –4095)
0
Broadcast
0
Broadcast
4
ARS31-UMB Active Road Sensor
1 - 4095
Available
15
Master or control devices
ID = 0 is provided as broadcast for classes and devices respectively. Hence it is possible
to transmit a broadcast on a specific class. However, this only makes sense if there is only
one device of this class on the bus.
6.1.3 Examples for creating addresses
If, for example, an ARS31-UMB is to be given device address ID 0001, this is done as
follows:
Class ID for ARS is 4d = 4h
Device ID is e.g. 001d = 001h
Putting the class and device IDs together gives an address of 4001h (16385d).
6.1.4 Example of a binary protocol request
If, for example, a request for the current freezing temperature (measurement range -40 ...
0) is to be placed from a PC to a road sensor with device ID 0001, this is done as follows:
Sensor:
Class ID for road sensor is 4 = 4h
Device ID (serial number) is 0001 = 001h
Putting the class and device IDs together gives a destination address of 4001h.
PC:
Class ID for PC (master device) is 15 = Fh
PC ID is e.g. 1 = 001h
Putting the class and PC IDs together gives a sender address of F001h
The length <len> for the online data request command 4d = 04h,
the command for the online data request is 23h and
the version number of the command is 1.0 = 10h.
The channel number is shown under <payload>; as can be seen from the channel list, the
current freezing temperature (-40°C ... 0°C) in channel 151d = 97h
The calculated CRC is C4D6h
The request to the device:
SOH
<ver>
<to>
<from>
<len>
STX
<cmd>
<verc>
<channel>
ETX
<cs>
EOT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
01h
10h
01h
40h
01h
F0h
04h
02h
23h
10h
97h
00h
03h
D6h
C4h
04h
The response from the device:
SOH
<ver>
<to>
<from>
<len>
STX
<cmd>
<verc>
<status>
<channel>
<typ>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
01h
10h
01h
F0h
01h
40h
0Ah
02h
23h
10h
00h
97h
00h
16h
<value>
ETX
<cs>
EOT
15
16
17
18
19
20
21
22
66h
66h
96h
C1h
03h
FFh
EAh
04h
<status> = Device o.k.
<typ> = Data type of the following value; 16h = float (4 bytes, IEEE format)
<value> = C1966666h corresponds to float value –18.8°C.

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 17
The freezing temperature is –18.8°C.
Correct data transmission can be checked with the aid of the checksum (EAFFh).
Important: Little endian (Intel, lowbyte first) applies when transmitting word and float
variables of such as, for example, addresses or the CRC. This means first the LowByte,
then the HighByte.
6.1.5 CRC calculation
The CRC is calculated in accordance with the following rules:
Standard: CRC-CCITT
Polynomial: 1021h = x16 + x12 + x5+ 1 (LSB first mode)
Start value: FFFFh
(Attention: Contrary to earlier Lufft protocols, the start value for CRC calculations is not 0h
but rather FFFFh in accordance with CCITT)
Further information is available in the description of a CRC calculation in UMB Protocol.
6.2 ASCII protocol
Easy communication with devices is provided by using the ASCII protocol.
ASCII protocol serves exclusively for online data requests and is not secured by a CRC.
The device does not respond to incomprehensible ASCII commands.
Using ASCII protocol, the measurements can be polled in a simple, insecure manner with
the aid of a terminal program. However, the sensor can only be configured by way of the
binary protocol. The output format is fixed and not user-configurable. You can find an exact
description in the document Communication Protocol for Meteorological Sensors.
After the HyperTerminal has started, select File -> Properties –> Settings -> ASCII
Configuration. Enter 1 ms for the character delay.
6.2.1 Construction
ASCII commands are introduced by the character ‘&’ and ended with the character CR
(0Dh). There is always a blank space (20h) between the individual blocks; this is
represented by an underscore ‘_’. Characters which represent an ASCII value are in
simple inverted commas.
6.2.2 Example of an ASCII request
If, for example, you want to request the current freezing temperature of a road sensor with
device ID (serial number) 0001 from a PC, this is done as follows:
A measurement of a specific channel is requested with command “M”.
Request: ‘&’_<ID>5_’M’_<channel>5CR
Response:‘$’_<ID>5_’M’_<channel>5_<value>5CR
<ID>5Device address (5-digit decimal with leading zeros)
<channel>5Gives the channel number (5-digit decimal with leading zeros)
<value>5Measurement (5-digit decimal with leading zeros); a standardized
measurement from 0 –65520d. 65521d –65535d define various error codes
Example:
Request: & 16385 M 00151
This request polls channel 151 of the device with the address 4001h.
Response: $ 16385 M 00151 62899
With the standardization for the freezing temperature the following calculation then results:
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Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 18
62899d corresponds to -40+(0+40)*62899 / 65520 = -1.6 °C
6.3 Channel assignment for the data request
The channel assignment described here applies to the online data request in binary
protocol.
All channels in the mapping standard are transmitted in ASCII protocol.
Channel no.
Measurement variable
Unit
Data Type
Measuring
Range
110
Act. Road Temperature
MS
unsigned short
0 ... 65520
111
Act. Road Temperature
°C
float
-40 ... +80 °C
112
Act. Road Temperature
°F
float
-40 ... 176 °F
150
Act. Freezing Temperature
MS
unsigned short
0 ... 65520
151
Act. Freezing Temperature
°C
float
-40 ... 0 °C
152
Act. Freezing Temperature
°F
float
-40 ...+32 °F
153
Act. FreezT no smoothing
MS
unsigned short
0 … 65520
154
Act. FreezT no smoothing
°C
float
-40 … 0 °C
155
Act. FreezT no smoothing
°F
float
-40 ...+32 °F
160
Act. FreezT. corrected
MS
unsigned short
0 ... 65520
161
Act. FreezT. corrected
°C
float
-40 ... 0 °C
162
Act. FreezT. corrected
°F
float
-40 ...+32 °F
801
Act.SalineConcentr.NaCl
%
float
0 ... 100
803
Act.SalineConcentr.CaCl
%
float
0 ... 100
805
Act.SalineConcentr.MgCl
%
float
0 ... 100
816
Act. Cryotech E36 by wgt
%
float
0 … 100
817
Act. Cryotech E36 by vol
%
float
0 … 100
818
Act. Safeway KF Hot
%
float
0 … 100
821
Act.SalineConcentr.NaCl corr.
%
float
0 ... 100
823
Act.SalineConcentr.CaCl corr.
%
float
0 ... 100
825
Act.SalineConcentr.MgCl corr.
%
float
0 ... 100
836
Act. Cryotech E36 by wgt corr.
%
float
0 … 100
837
Act. Cryotech E36 by vol corr.
%
float
0 … 100
838
Act. Safeway KF Hot corr.
%
float
0 … 100
900
Act. Status GFT-Measuring
n/a
unsigned short
0 … 5
901*
Act. Threat of icing
n/a
unsigned char
0 … 2
1049
Act. Road Temperature
TLS FG3 DE 49
signed short
-300 ... +800
1052
Act. Saline Concentr.NaCl
TLS FG3 DE 52
unsigned char
0 ... 100/255
1065
Act. Freezing Temperature
TLS FG3 DE 65
signed short
-300 … 0
1073
Act.Saline Concentr. NaCl
TLS FG3 DE 73
unsigned char
0…100/255
3001
Act.Saline Concentr.MgCl
TLS FG3 DE 52
unsigned char
0…100/255
3002
Act.Saline Concentr. CaCl
TLS FG3 DE 52
unsigned char
0…100/255
3011
Act.Saline Concentr.MgCl
TLS FG3 DE 73
unsigned char
0…100/255

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 19
3012
Act.Saline Concentr. CaCl
TLS FG3 DE 73
unsigned char
0…100/255
20001
Act.Measurement Counter
n/a
unsigned short
0…65535
Legend:
MS ... Mapping standard
* ARS31-UMB doesn’t support Channel 901.
Difference between the “saline concentration” channels 801, 803, 805, 816, 817, 818,
821, 823, 825, 836, 837, 838, 1073, 3011, 3012 and the channels 1052, 3001, 3002:
The channels 801, 803, 805 etc. deliver saline concentration in percent by weight. For
example a solution of NaCL with a freezing temperature of -5.3°C reports a measurement
value of 8% on the saline concentration channel 801. The channels 1052, 3001 and 3002
are based on the saturation of salt in liquid. For example a solution of NaCL with a freezing
temperature of -5.3°C reports a measurement value of approx. 36% (8/22 in [%]) o channel
1052. The maximum saturation of NaCl in water is about 22 percent by weight.
Difference between corrected and uncorrected measurement channels:
In the case of uncorrected channels, the status of the channel in the UMB protocol is used
to classify the measurements; if, for example, the ambient temperature is too high the
status can not be 0 (e.g.: 84, the possible error codes are specified in the document
Communication Protocol for Meteorological Sensors); in this case the freezing temperature
is neither calculated nor transmitted.
In the case of corrected channels the status is transmitted on channel 900. If it is not
possible to calculate the freezing temperature, this is then transmitted as 0°C (or its
equivalent in other units).
Status generation and freezing temperature on the corrected channel:
If it is not possible to calculate the FT status because the ambient temperature is
greater than the temperature set for the sensor (factory setting 5°C), the FT status
is set to 0 and the freezing temperature value is set to 0°C.
If it is not possible to calculate the FT status because the road is dry, the FT status
is set to 1 and the freezing temperature value is set to 0°C.
When a valid FT is calculated, the FT status is set to 2 and the freezing temperature
value is set to the calculated value.
If it is not possible to calculate the FT for other reasons the FT status is set to 3 and
the freezing temperature value is set to 0°C.
If it is not possible to calculate the FT status because the ambient temperature is
lower than -30°C, the FT status is set to 4 and the freezing temperature value is set
to 0°C.
If it is not possible to detect the freezing temperature, because it is below the limits
of the sensor, the FT status is set to 5, freezing temperature below road
temperature -20°C (Tg < (Tu –20°C))
If it is not possible to calculate the freezing temperature, “0” is transmitted for freezing
temperature and “255” is transmitted for “residual salt” on the TLS channel.
A sensor with factory settings will deliver a value of -0,1°C in channel 1065 (freezing
temperature TLS) whenever the road is wet and without salt. The reason for this output is
that in the (German) “Bundesdatenverteiler” (12/2010) the TLS compliant combination of
0°C freezing temperature and 0% residual salt are causing errors in the visualization.

Operating Manual ARS31-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany 20
6.4 Mapping standards
Mapping standard
Temperature measurement range
0 –65520
-40 ... +80°C
-40 ... +176°F
Freezing temperature measurement range
-40 ... +0°C
-40 ... +32°F
Salt concentration measurement range
0 ... 100 weight %